I agree with you that a lot of literature regards Flame Angelfish as a hit or miss in a reef setup. Some folks have good luck and others don't recommend putting them in with corals.
I've had a Flame in my 55 reef tank for about 8-9 months, and so far it's never picked at any of my corals that I know of. It does nip at the live rock now and then, and I keep some nori seaweed on a clip. Occasionally it picks at that.
Flames are beautiful fish for sure ... colorful and very active.
I'd guess that for every hobbiest that successfully keeps one in a reef, there is a person that ends up getting one that picks at everything. Of course this is just a guess.
Don't know what else to say about Flames, except again they are really cool fish !
I have been unlucky with Flame angels. I had two recently, one in a reef tank, the other in the fish tank. The one in the fish tank starved to death for 2 weekw although he was pecking at the glass. He never recognized food as food (I tried all kinds of food). He eventually "committed suicide" by rolling itself into an empty large shell. The second one is in my reef tank. It has been there for more than a month and did not attack any corals. HE is nipping at live rocks though. I feed him frozen PIGMY ANGELFISH and he loves it. He is quite friendly but seems to suffer from popeye now.
Flame angels are beautiful but maybe not too hardy?
My flame picked at most everything at first, but after a few stings and a little time, he realized what to eat and what was not food. Now he leaves every coral alone. Picking at corals is often normal with this fish, but it is alot different than if he was eating them. No corals were seriously damaged by the picking. Hit or miss is a good way to put it.