Four of us went there last Thanksgiving and began with Fred Riger based on a recommendation on a different board.
We made the mistake of showing up on a Sunday and dove a 12 foot reef. Evidently, that is his Sunday routine. Had we realized that and shown up on a different day of the week, I'm not sure we would have continued to dive with Fred. His operation appeared safe, his boat was in good condition, it's not hard to get to his shop, and everyone was personable but Fred had his own timetable on when things happened. He's been there a long time and he's been successful so it must work for him but it didn't work for us. You may want to use him if this fits your style of diving and vacation time.
As I wrote, we showed up on Sunday for his 1 tank dive and we left two hours after the time he told us we'd be leaving. During our week of diving, we were typically getting back onboard the boat after our first dive and we'd see Fred coming out to the reef.
We ended up using Carribean Diving, mainly because it was based at the place where we stayed. They treated us well and our bottomtimes were based on our air consumption. The only drawbacks I could see were the tanks being filled to 2800 psi and the DM not being real good at pointing out things but being more of a tour guide and being there to point you back to the boat.