I have a pyramid butterfly and it has never picked at anything. I have a copperband, too, but it is still in quarantine learning to eat frozen food. It did eat the aiptasia that I put in the q-tank. I don't have any feather dusters in my tank, so that won't be a problem.
I have read that the Forcipiger longirostris is fairly reef safe, but have never owned one. They are almost impossible to find. My LFS complains that even when they try to order one, the wholesalers send F. flavissimus instead. Because of their specialized snout, they can be a challenge to feed. I have an idea for a live brine shrimp feeder constructed along the lines of a hummingbird feeder if I ever find one of these fish.
My next butterfly will be a Chaetodon miliaris, the lemon butterfly. They are probably a little more risky, although they are plankton eaters in the wild. I am waiting until my corals are grown out more, since they will then be able to withstand the occasional nip better than now.
One key to keeping butterflies, both for the sake of the tank and the fish, is to feed them often. If they are hungry, they are more likely to sample the corals. I feed mine three times a day and am planning to add an automated feeder to provide a mid-day meal. These are small feedings, since I don't want to fuel algae growth in my tank.
You may have to choose which you want more, that open brain coral or the butterfly. I am willing to lose a coral here and there so that I can keep these fascinating fish.