So I finally did it, as I've been talking about for a while.
I tried both IMBC and SMBC. I clearly need some guidance and I know you guys will have the answers! (I discovered my candy thermometer smashed in the back of my drawer, so I did do some guess work based on further research for both, but anyway)...
Question #1: IMBC (Cake Bible Mousseline Buttercream): To get sugar temp close, I dropped some in a glass of cold water. Reached soft-ball stage. Slowly poured sugar into meringues, and it sounded gritty, like the sugar was just getting stuck and just beat around the bowl. Sugar cooled quickly in measuring glass and some of it stuck to the side and didn't end up in the icing. Slowly added butter. Tasted like only butter. I ended up adding PS to this and was able to recover it! But I still think I need some help.
Question #2: The COMPLETE DISASTER: SMBC. Used the recipe her on CC by admin. Noticed it wasn't complete, so followed directions from baking911.com for the process. Everything seemed fine. Too soft, but fine. Put completed icing in fridge for 20 minutes and re-beat. Seemed great. But had more work to do on cake. Put icing back in fridge for about an hour.
Icing seemed to have dried out. It was like it crusted all the way through. I tried mixing it up with my spatula a bit and it DEFLATED! It shrunk down and took up about 1/3 less space in the bowl. Then, it started oozing. I could see liquid like it was coming out of "pores" for example. I loaded up my bag to see what would happen. So gross, it was like squirting out, too-stiff icing combined with complete liquid squirts that started running down the cake.
What happened here?
Scraped the small amount I had completed off and covered with ganache as it was 11:45 pm by now!
Question #3: Think there is anything I can do to recover all that wasted egg and butter from the SMBC - a filling or something?
Question #4: One obvious answer might be the temperature of both icings as I didn't have a thermom and I'm getting a good one this weekend - Any suggestions for a particular one (instant digital is what I understand I should have?)
Any help is greatly greatly appreciated!
Thanks 
Sorry to hear about your disasters, so discouraging. I have never made SMBC but with IMBC I have had something similar happen to what happened to your experiment no 2. When I have re-beat IMBC which has been refrigerated it has separated completely. Solid lumps of fat with liquid oozing around it. Looks really gross. But I just left it in the KA on low for a really long time, maybe 20 minutes or more. Eventually it came back together and was just like it was when it was first made. I have since learned to bring the IMBC back to room temperature before beating it, or put a hot wet towel around the bottom of the cold bowl to speed up the process. Just be patient, it will come together in the end.
Good luck,
BakingGirl
Sounds like the SMBC Broke. I use ice cold butter when I make this. I will whip it until creamy smooth but will stay a bit firm. It is different to work with and softer but should go on nicely. If you chill it it will break during the beating process. It needs to come to room temp first. If there is not time you can whip it for five to ten minutes. I also will taake a blow torch and touch the outside of the bowl.
Sounds like the sugar syrup cooked a bit long. Remember that it still cooks after taken off the heat. Ulnless you shock it it can get to the next stage of cooking.
thanks for posting this link in my topic! Mine did the same thing - became all watery ickiness..... guess you gotta put it back in the KA - I like the warm towel wrapped around idea though to help it come to room temp. quicker.... I'll have to try another go at this..... how long can it stay in the fridge? if I tried using it and it got all watery can I still save it or should I throw it out? What if you froze it? How long should you let it sit out to defrost/come to room temp. before trying to beat it again?
Oh and did you have problems w/ icing "holes" in the swiss buttercream? Like those big pock marks or indentations in the icing??
I never got so far as to find any big bubbles causing holes in my SMBC. I was trying to pipe big rosettes all over the cake for a super quick icing.
But then I tried to smooth it over the top and it nearly pulled up the top of my cake!
I kept the bowl in the fridge. This weekend I'm going to try to rebeat it (only after coming to room temp, now that I know!) and see what happens!
I thought my recipe said fridge for a week, frozen for 3 months or something.
Hopefully we'll figure this thing out! I'd love to get it right!
Good luck to you imartsy! Be sure to post anything new you learn, I will too.
Were you careful to pour your hot syrup down the "sides" of your KA bowl and not let it touch the whip? It sounds to me like the reason you got grittyness is because the whip got ahold of your syrup and it WILLl make crystalized sugar. Its very important to pour that hot syrup carefully down the side of the bowl "between" the whip and the side of the bowl so it doesn't catch the syrup until it has incoorporated into the egg whites in the bottom. Just a thought to consider.....I had that happen once and got spun sugar! 
... I discovered my candy thermometer smashed in the back of my drawer, so I did do some guess work based on further research ...
Question #1: IMBC (Cake Bible Mousseline Buttercream): To get sugar temp close, I dropped some in a glass of cold water. Reached soft-ball stage. Slowly poured sugar into meringues, and it sounded gritty, like the sugar was just getting stuck and just beat around the bowl. Sugar cooled quickly in measuring glass and some of it stuck to the side and didn't end up in the icing. Slowly added butter. Tasted like only butter. I ended up adding PS to this and was able to recover it! But I still think I need some help.
Question #2: ... Icing seemed to have dried out. It was like it crusted all the way through. I tried mixing it up with my spatula a bit and it DEFLATED! It shrunk down and took up about 1/3 less space in the bowl. Then, it started oozing. I could see liquid like it was coming out of "pores" for example. I loaded up my bag to see what would happen. So gross, it was like squirting out, too-stiff icing combined with complete liquid squirts that started running down the cake.
What happened here?
Question #3: Think there is anything I can do to recover all that wasted egg and butter from the SMBC - a filling or something?
Question #4: One obvious answer might be the temperature of both icings as I didn't have a thermom and I'm getting a good one this weekend - Any suggestions for a particular one (instant digital is what I understand I should have?)
Any help is greatly greatly appreciated!
Thanks
Poor Baby!!! 
Fear not, we're here to help!
ANSWER #1: I don't ever transfer my sugar syrup into a glass measure when I make the Mousseline Buttercream. Too much hassle, and it seems to cool off too quickly and it doesn't all end up in the meringue, as you discovered. I pour straight from the pan into my KA bowl with the motor running! There is a VERY NARROW space between the whisk and the bowl edge that you can pour in a "steady stream". This works for me every time. Yes, it will taste like slightly sweetened, sticky butter, but a lot of my Clients prefer the taste. I generally tell people that this is the icing you want if you don't like it so sweet your fillings scream when you walk into the room with the cake 
! If you want a more interesting flavor next time, melt about 6 oz. of white chocolate (obviously the better the quality, the better the taste). If you close your eyes, and really concentrate on the flavor, it's faintly of the last drops of a rootbeer float at the very bottom of the glass ... slightly sweet but not overpoweringly so, not at all unpleasant. Yummy. I think this icing is a really nice support to most cake flavors ... it doesn't compete for attention in the mouth.
ANSWER #2: Deflated/liquid: Pay attention to the tips in Rose Berenbaum's book. This type of icing gets "spongy" when it sits: i.e., the air bubbles you whipped in when you made the meringue are now going to set, and once you've let the icing sit, if you stir it down, they'll pop a bit, which will deflate your icing. It makes for a smoother icing at that point, but much less volume. Put it back on the mixer and whip it up for a bit again. As for the liquid-y stuff: your icing is "breaking". Again, what it needs is time on the mixer with the wire whip. It may take some time, but it should come back together.
ANSWER #3: Put in some fruit puree and turn it into a filling. Raspberry with perhaps a little bit of raspberry liqueur ... yummy! [and if you eat enough of it, you won't care about the problems you had earlier!!! 
]
ANSWER #4: Yes, you really DO need to have a good thermometer. I currently use a digital one that has The Good Cook on the face of it ... I think I got this one at the local Kroger store one night when I really needed it and I was quite desperate! The only reason I didn't buy a more expensive one is that my family tends to break things, although not necessarily on purpose, and this one has just lasted me the longest! I probably paid all of about $10 for it, if that!
So, fear not, czyadgrl, take heart. I know learning this kind of icing is a really daunting task, and it's a learning curve. Just be willing to tough it out and stick it out and you'll get it. You won't regret having mastered it once you do! (I keep thinking that I want to be able to do rolled fondant, but every time I try it, the stuff just tastes awful, cracks all over the place, stretches, sags, and bags off the sides of my cakes. How I admire all those bakers who can do it. But SOME DAY, by golly, I am going to master it! I've got determination! And if I don't, then .....
well .....
I just won't care any more!!!)
Hope this has helped you out. If you need more info, PM me and I'll try to talk you through it even more.
Odessa
I use the Italian meringue recipe where the egg whites are beaten to stiff peaks with the wire whisk attachment and the cooked syrup is poured over the beaten whites. I also cut Martha Stewarts recipe to 3 sticks of butter rather than 4, too buttery otherwise. Having an accurate thermometer IS important but there is another way of checking it. Sounds strange but it actually works well. Use a slotted spoon, as the syrup is cooking dip the spoon into the syrup, lift it out and blow through the slots. The minute the syrup forms a bubble through the slots, like a childs soap bubble, it is done. Remove from heat immediately and pour it slowly but steadily between the beaters and side of the bowl, have the mixer on a medium low speed. When all the syrup has been added beat on high speed until the outside of the bowl feels cool to your hands. Switch to the paddle beater and add the butter a few pieces at a time on medium low speed. When all of the butter is incorporated turn the speed to high and beat until the icing comes together and is shiny, the bowl feels cold to the touch of your hands. Add flavoring, beat to combine and it's done.
Here are a few tips that I have learned by trial and error
Have the butter slightly chilled, not hard but not room temperature either, just so there is a bit of give when you push it with your fingertip. Have it cut into pieces and ready to go before starting your icing. You can put it back in the fridge and take it out as the syrup is cooking.
Don't pour the syrup too quickly into the beaten whites, it will deflate them. But not too slowly either or the syrup begins to set up too much.
If the icing looks curdled after adding all of the butter don't panic, keep beating on high speed and it will suddenly come together.
If you have refrigerated icing in a bowl it has to come to room temperature before rebeating it. If it is too cold it will break or separate and you will see liquid at the bottom of the bowl. If this happens it can still be saved, let it warm up a bit and beat again, start on a low speed until it begins to come together, then turn mixer to high speed and beat till fluffy.
And I find by adding half a capful of orange extract along with the vanilla gives the icing a nice flavor. It cuts the sweetness but doesn't really taste orangey, just a nice fresh flavor.
Those hard gritty lumps you were sensing were lumps of sugar that had cooked too long or at too high a heat source. It will never come together smoothly with those in the icing, you need to toss it and start over.
Here is the recipe I use.
4 egg whites beaten to stiff peaks with wire whisk attachment while syrup is cooking
Syrup ingredients
1 1/4 cups granulated sugar
pinch of Cream of Tartar
1/3 cup water
Cook to 240 degrees.
3 sticks butter (12 oz.) chilled but not hard, cut into small pieces.
2 teaspoons Vanilla and 1/2 capful of orange extract.
Pour syrup slowly but steadily over beaten eggs whites and beat till bowl is cool to the palms of your hands. Switch to paddle attachment and add butter a few pieces at a time, beat till bowl feels cold to the touch and icing comes together and is shiny and fluffy, add flavorings and beat till combined.
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