A couple more notes- I took my family on another Stingray City Sandbar trip with a second company, so have a little more data for comparison.
Things I really liked about the Diver's down trip:
They started early- We were the only boat there, which was very nice. On my second trip we also went in the morning, but were one of 14 boats when we got there (I made the mistake of going on a day cruise ships were in).
The Videographer put in a lot of work. I did not catch her name, but she was in the water literally before the boat was anchored with scuba gear on, taking video before the water got mucked up. She also dove while the group snorkeled later and took a lot of video of the group, people waving, and even drew out some large eels. She was heading in to convert the tape to a DVD with music and titles and all after the trip, with delivery to your hotel later that day. Her price of $60 for the DVD seamed too high to me at the time, but I would have liked to have seen it.
The snorkel portion was on a nice reef section, not just some heads on the sand flats. A good location, with lots of life.
Things I would have changed:
The boat was a three-pontoon boat, with about 75% shade. We all got pretty wet with the spray on the way out. The boat had no head- I had a 3 year old with constipation issues that week, and no head was a significant concern.
One more person on the boat would have been nice. Only the Captain and the Videographer were on board this trip. When they were both in the water, no-one was on board to help people load/unload or to help exchange gear. Not a big point, but when my later trip had three people plus the Photographer, I did appreciate the extra help being around.