I go SMBC over IM because it's easier to make for small quantities and I'm small time. At this point I don't even use a thermometer when cooking my whites because I can tell by sight and steam if they are at 160, you can't tell that with syrup for true IMBC.
I am getting much busier though, when I get past the point where I can no longer produce the quantities of SM that I need in my trusty KA, I'll have to start using the big Hobbart making IM (no way I can hold a 60q bowl over a pot of water)
Anyway, I'll probably try and perfect neo classic IMBC to prevent overcooking disasters trying to use organic agave instead of corn syrup to fit more with my mission statement.
I use all my yolks in my yellow cake, which is my default "white" cake for normal orders. I only do true white for wedding cakes.