I love smbc... I haven't tried imbc yet but from what I understand they basically taste the same so I go with the one that doesn't require tempering eggs.... I'm not usually successful with that. It's whatever works best for you.
It doesn't crust, but when you crumb coat, you just put it in the fridge til its hard, then ice over it. Add too much icing than you need. Return to fridge and let it stay for about 30 minutes. Then bring it out and you can use a knife and shave off what you don't need. I've never done the hot knife as it can change the colors of the icing, and ive never needed to. I could never get perfect edges with American buttercream... I have tried and tried and sometimes I couldn't even get it all smooth. My first try with smbc, it was beautiful!
If covering with fondant, I make sure it's absolutely cool... So I normally do my icing at night and do my fondant in the morning. I also always use a ribbing of piping gel around the botttom to get the fondant to stick...
I've altered the recipes I found to find one that suits my tastes. I use 8 whites, and 2 cups sugar. I only add 2lbs of butter as well. It still has the butter flavor, but doesn't taste like straight butter. If you have a 5qt mixer, this is about the max of egg whites you can do... 12 whites overflowed in my mixer lol... I also use my metal mixer bowl as my double boiler and put it straight on the mixer. I've tried using a hand mixer while heating and it didn't work so well so just use a whisk. Make sure your candy thermometer is in good working order too. Hubby put mine in the dishwasher and it ruined my next batch.
I also add 1/4tsp cream of tartar to my egg whites when I start my mixer... I start on like a 3 for about a minute and then go to 7 and walk away. Come back 10 minutes later and usually I'm ready for butter. Just make sure the bottom of the mixer bowl is no longer hot before you add butter. Make sure your butter is soft, but not melted. I usually take my butterr out, cut it in 1tbsp sections spand let it sit out about an hour or two before i make my icing. I switch to the paddle, add all my butter in, and turn the mixer on a 5-7 and walk away. After about 10 minutes it's usually all incorporated. Add your extract or color, mix on low and tada... The best stuff you will ever use!
The pics there are great. Smbc goes thru stages and it freaked me out the first few times....