I have had a one spot foxface since before I had any type of coral, my advice is to get one small and offer it plenty of vegetation. He has not bothered any of my corals until recently he may be pecking at my bubble coral. But that's how I know when its time to feed my tank. Spot is a pig, if I put a piece of domain in there he won't stop till its gone.
to make a long pointless story short, if you get a foxface rabbitfish make sure you have an escape plan. I imagine that if one were to begin eating your reef, it wouldn't stop until it was gone. They grow fast also, fast like an Oscar grows.
oh yeah. The poop alot also.