I have always made a crisco only based buttercream. i have been searching for a good chocolate buttercream recipe, and most of the ones I have are either all butter or butter/crisco. How much do I have to worry about using butter in an icing? Does this mean I need to refrigerate my cake before serving? If I cover my cake with fondant, can it still be refrigerated without making the fondant gross? The cake has to travel for 2.5hr to the wedding, can it stand to not be refrigerated?
My BC is always half butter and I have had no problems with it not being refrigerated. I do find it makes my BC a little more soft, but not horribly so. I do prefer to use a butter/crisco BC under fondant instead of all butter because I am always concerned about the moisture content in all butter against the fondant, but maybe someone on here has actually tried all butter and has better advice.
The sugar acts as a preservative, so it will be perfectly fine not being refrigerated. The last time I used Crisco in my BC was for my Wilton class... only use all butter now, and have never had a problem. HTH