Report back! Dove with Caicos Adventures (Bernard was our DM). Great outfit. Unfortunately my wife was feeling sick so we could only do one two-tank dive and a night dive. The upside was we got to enjoy quite a bit of other island activities.

Below is a summary of the dive trip:
Caicos Adventures picked us up right on time from our hotel. The two tank dive went out to West Caicos. The catamaran was out for repairs, so we went on the Hercules (a smaller boat). There were just three other people with us. The weather was nice, but the sea was choppy, which made for a fairly choppy 40 minute ride. We didn't mind as we had good company. We opted to dive Nitrox. The DM analyzed the gas on each tank in front of us.
First dive was to Pickering Place. We saw four reef sharks on the first dive (plus a lot of other cool things). We spent the surface interval in the private protected harbor of the abandoned resort where the sea was very calm. We were provided sandwiches, chips, and non-alcoholic drinks. Second dive was to Tons of Sponge, where we saw four more reef sharks at the same time (including a six footer which followed us for a good 5 minutes). I would say the second dive site was more impressive, although both were great.
The night dive was from the shore of Coral Gardens hotel (where Caicos Adventures has a small shop). It was a private dive with Bernard. The dive is very shallow (our max depth was no more than 30 feet), which gave us over an hour dive time (with about 800 PSI still left for me). Really cool experience. We saw a ton of lobsters (including a Spanish lobster), an octopus, many puffer fish, a turtle, and quite a few sleeping fishes. I'm told reef sharks occassionally visit the area as well.
I was also lucky enough to be there on the last day of the glow worm mating (five days out of the month). Bernard wasn't sure if we'd be able to see any glowworms, but promised he'd try. On the first try we didn't see any and decided to keep going. Prior to ending the dive, Bernard signaled to try a different site. After getting onto our knees in a sandy area and turning off our flashlights, the glowworms began their dance, which was a really cool experience. I highly recommend you check this out if you're there during the days when they're mating.
Overall I was very happy with the outfit, our divemaster Bernard, and the dive sites were excellent. The reefs at our sites weren't as colorful as I recall of Cozumel, but the large pelagic life is clearly superb (8 sharks on two dives isn't a bad haul!). The two gentlemen who were a part of our dive group saw a hammerhead a few days before and sharks on most dives.
A few words about the island: the beaches are absolutely incredible. Definitely check out Taylor Bay Beach, Long Bay Beach, and Sepadilla Bay Beach if you're ever staying at Turks & Caicos.