My flame angel so far (5 months) has not been a problem with the mushrooms or polyps, or anything else. Also, the flame, the kole tang and the yellow tang all seem to get along well.
I have heard, and I think read (perhaps in the Fenner book) that copperbanded butterflies aren't the best choice among butterflies even for a fish only tank. Ive heard that either raccoons or long-nosed are hardier, more peaceful, less finicky eaters as well. I would like to know if either raccoons or long-nosed butterflies are OK with soft corals.
If my tangs outgrow the tank, I will move them.