I recently was able to pick up a pair of Moorish Idols and they are beautiful fish. This pair was originally hand collected in Hawaii and overnighted to a customer the the SF Bay Area that eventually ended up having to take them to the LFS. I happened to be in shortly after this and took them home to my 450 gal. reef tank. There was a little difficulty in getting them to eat but they are now very rowdy eaters. I fed live brine shrimp initially but now they pig out on frozen krill and mysis along with Formula 2, nori, flakes, diced shrimp, mussels (they love mussels!) and most anything else I feed them. I've given them a few of the small sponges that grow in the dark sump and overflows but in general they don't get sponge in their diet. They remain fat and healthy after 3 months (this is a short time but it is looking good so far). They haved ticked off the emperor angel who thought he was king until this pair of new fish showed up (one is about 6" in length and the other is slightly smaller at 5"). He periodically chases them around the tank before returning to sulk in his cave but they seem to effortlessly zoom away from him. To see the pair of them doing a synchronized parade back and forth in the tank is a magnificent sight. At times the sailfin tang likes to tag along and swim with them. None of the other fish seem to bother them other than the foxface likes to try and steal krill from them. Other tankmates are a flame angel, 2 lyretail anthias, a horde of tangs (4 yellows, blue, purple, the aforementioned sailfin), a school of bluegreen chromis, and a clownfish. There is a lot of SPS, mostly acros and limited LPS, although I have about 2 dozen ricordia florida. I have not seen the Idols going after any of the coral but I purposely feed the fish a lot so that they will be less tempted about going after the coral. The Idols pick on stuff on the live rock but they eat enough at feeding time so that I don't think they are very hungry most of the time.
One interesting note, within 18 hours of adding them to the tank they both showed significant crypt symptoms (20+ or so white spots). I didn't think I could catch them without harm and I couldn't treat traditional crypt/ick medication without taking out many of the inhabitants of the tank. I started adding Kent Garlic Extreme to their krill and mysis, soaking it for 20-30 minutes before feeding. Within a week the spots were gone and they have not come back. A number of other fish (all of the tangs) developed spots shortly after and they also recovered without any losses. I was surprised how "easy" this was. No other fish has shown white spots since (other than the blue tang which now seems to have a chronic problem with this and spots show up every week or two - but only for him).
I'd be very interested in hearing form other Moorish Idol keepers about their experiences including feeding strategies and issues to look out for.