I am very sure you can keep flame angels in a reef. I love my angels. I never have much problem with my Flames and Regals. I do have mix reef with LPS, SPS, Clams, anemone and even soft corals. I think I tolerate minor picking, if any, from my Angels. My SPS do not have great PE, but they grow very well.dang Orion, you're making me want to try Flames again. I struck out with all of mine being nippers of everything. Tremelle, more pictures please.
Here is one of my two baby Regal Angels. I am happy to reports that they get along very well and I am likely end up with a pair. They are still very small, only about the same size as my Flame Angel pair, which are about medium size for Flame angels.