`I have worked with fondant a few times and usually use basic shortening based b/c underneath it.
I have used other icings before with fondant accents and it tends to slide off the cake. (in my gallery the mother's day quilt w/breakfast tray) Is using anything other then b/c asking for trouble? Not to mention the kinds of icing I am using are supposed to refrigerated and from what I have read fondant doesn't go in the fridge once it is on the cake.
I have always used BC under fondant, thin layer only. And I have put fondant back into the fridge after it's on the cake but only for overnight and have never had an issue with moisture spots but some here have had that issue. Never ever put fondant in a freezer or on a frozen cake. If you freeze your cakes then go ahead and put the BC crumb coat on but then give it a couple of hours to thaw and crust up before adding on the fondant.
The times I've tried to put mmf in frig, is was bad. So I learned to just not do it. I use bc (all short) under mine, but recently tried ganache and it's a charm, holds up good and taste better. Gives crisper edges too.
I always use buttercream under my fondant.