I have been a F/O person for five years now, and just recently bought live rock, for the sole purpose of keeping my fish happier and healthier. They are unsurpassed at keeping water quality good, and alot of my fish are the grazer variety and they appreciate the good algae on them. (tangs and pygmy angels) The only problem I have with live rock is that you're never really sure of what is on the rock. Like anenomies, shrimp, snails, and whatever else. So far both my fish and I have really liked the hybrid of reef and F/O.