I have had several over the years and none of them really had a taste for corals. They constantly scavenge and pick at the reef so occasionally on their way past a clam or something, they will take a nip. Nothing a healthy coral or clam can't handle. That is just my experience, your mileage may vary.
A lot of people say they are hit and miss. From what I have read and heard others say, it seems like they do best if they are in an established aquarium and are well fed. If the corals are well established and healthy, they should be able to withstand the occasional nip, and keeping the fish fed with other foods will reduce the amount they nip at corals.
I have had a pair of Flame Angels in my reef from the start. The only issue I have had is that they would some times nip at the mantle of the LPS type corals and keep them from fully opening. I had to remove my open brain coral and some acans because the polyps were not opening, no damage to the coral just looked much better in my other tank.
I now have a pygmy angel in with corals. I do not have acropora or clams in this tank, but do have frogspawn, zoa's, shrooms, ricordea, etc. No problems, so far.
I had a flame angel that picked at corals constantly. The bigger issue though was that s/he was a bully in the tank and just too active for my taste. Took me months to catch the bugger.
I had a coral beauty in my old 58g and a cherub in my 15g back in the day. Neither of them touch anything...UNTIL I put a clam in there, then in both cases they started nipping the clam and within a week were pecking at LPS. They were evicted shortly after.