I don't have one, but from what I've heard, it's a bit risky to keep them in reefs. Like dwarf angels in a way, they're hit or miss, basically. Some people have reported problems of copperbands nipping at their corals, and some people have said they've never caused them problems.
My advice is that if you're going to get one, get one as small as you can. Chances are better that it's less likely to nip at corals when it grew up around them versus if it was introduced into the tank as an adult. JMO.
Either way, good luck!
PS. If you're thinking about them for apitasia control, there have been a lot of good things said about peppermint shrimp for that.