Angels and Bflies are not really reef safe - the least damaging (according to most) is the copperband Bfly - with either species, you are taking a chance at picking -
The Dwarf angels, are also, least likely to feast on your SPS's - the cherub is one of those that many keep in their reef. I have heard that as long as you keep them happy with food, they usually won't pick - to me, the calculated risk isn't worth it - but again, that's my decision -
Hope that helps,
House