My wife and I were on the T&C Explorer II in late April of this year. Very highly recommended. The crew was amazing, the food was terrific, and the diving was the best I've done so far. We spotted reef sharks on virtually every dive, and as diversteve said, there were so many stringrays that they almost became boring. Lots of nurse sharks, too. At one point I was trying to take a picture of something, and a nurse shark kept swimming in front of the lense, getting in the way. It was almost like a puppy that's upset because you're not playing with him.
We had good, but not perfect weather. Captain Ken reversed the normal route so that we were protected by West Caicos when the wind kicked up mid-week. Despite some moderate wind at French Key, which we visited first and is out in open ocean, nobody had any issues with seasickness.
When we went, there were 13 divers out of the maximum of 20. It was a nice size group. But the boat is large enough that even at maximum capacity, I don't think it would feel crowded.
The rooms were nice. We had room #6, in the middle of the boat, and we had a king size bed with 3 or 4 feet of room around two sides. The en suite bathroom was small but adequate.
The diving and eating schedule is run with military-like precision, which I really liked, as you're never sitting around wondering what's next. Two dives in the morning, two in the afternoon, and one night dive. Six of the 13 of us did every dive; a couple people did only 2 or 3 a day.
Again, a great experience and one that I would recommend with no hesitation.
James