I don't think any dwarf angels are completely reef safe - and the conditions that make one individual a model citizen in one tank and a second a terror in another tank are unclear. Individual differences, tank mates, coral and invert choices all probably make a difference. I'm a huge fan of these fish, and unless one is leaving a path of destruction in his or her wake then I'm inclined to be 'understanding'. My faves, not necessarily in this order, are Flame, Potters, LemonPeel and the RedStripe. I'd love to have all four in my tank, but have been unable to find the courage to try. I currently have a fairly large Flame in my mixed reef. He is generally well behaved, though my open brain coral is looking a little peaked, I suspect, from the occasional nip. I also have a Potters in my min reef/QT that will go into the main DT once it has put on a bt of weight. I'd not seriously consider a LemonPeel for a reef tank though. My LFS currently has a RedStripe (as well as a mimic, which might be a better choice) and I'm sorely tempted.