If you look on RC the tank of the month has a Regal angel in it and it seems to be fine.
That being said Regal angel are very hard to get to eat and most don't make it. They will pick on the live rock and may go after soft coral, polyp and zoo's so there is a chance but that also go for alot of the angels.
If you want to try one get a very small one, as there is a better chance of it eating than a larger one. Alot of people get them to start to eat by placing mussels or clams, with the shells, in the tank so the Regal angel can pick at them.
If your going to try a Regal, try to get one originating from the Red Sea. They fare much better (although the success rate is still dismal) than the ones from the Philipines or Indian Ocean. Plus they are much more colorful than their counterparts.
I had a regal a while back in a fish only tank. It never ate so I moved it to my quarantine tank which housed some live rock and a baby fuscus trigger. The fish started eating and I moved it to the main tank, where it lived happily for close to a year. It ate right out of my hand. Sadly I left town for a 3 week vacation and my tank sitter opted to flake out on me and I lost everything in the tank.