I like buttercream because it has real butter in it. I have had this ongoing debate with my cake friend for a few years! I do lick her "BC" beaters though -used with high-ratio shortening and 10x. I make SMBC because I like the creaminess and shine. I really
don't like the 10X feel in my mouth, which is mostly what one has to use with shortening. And I HATE
measuring out 10X and working in a white cloud!! Also, high-ratio is harder to find now that Crisco changed. I easily get my butter at Sam's -unsalted.
Basically everyone in my area uses shortening based frosting -home based and big bakeries, so I'd like to target that "gourmet foodie" market, that I'm a part of. I advertise I use real butter, real eggs, and no mixes, and my customers really appreciate that statement.
BTW, I love the Cake Bible, and her butter-based cakes, which a lot of American's don't care for compared to oil-based mix cakes. Again, I like to target a different market, and make what I personally like. BTW, I do add a little more sugar into my SMBC than a lot of recipes, and less butter -so it's like 7 minute frosting with some butter -YUMMY!!!