I've had my copperband for almost 4 years now. It is in my 180g tank. It has never shown any interest in my sps and the only interest it had in my clams was if they were on the sand bed. Long as the clams were in the rocks, which being the species of clams I had they should of been in the rocks, the copperband was fine. My copperband just loves frozen mysis{PEbrand} and will also snack on enriched brine too.

As to the pearlscale butterfly I know of a member on another forum keeping one quite successfully in his reef. BUT that is not an endorsement, most bytterfly fish are not considered reef safe by any means.