I stayed at Scuba Club Cozumel last September, just in time for Hurricane Isadore. The diving we did was great, and even though you're on a cattle boat, they broke you down into small enough groups that you weren't in huge mobs underwater. Groups of 8 aren't too bad. The DMs were really good. They even were willing to venture out into rough water with a bunch of water-starved hurricane-grumpy divers from Florida who just wanted to get wet on our next-to-last day there.
Shore diving was good. Plenty of life, even if it wasn't on corals. There is a resident octopus living under the dock, and plenty other life to keep you interested whenever you want to get wet.
The food was good, the rooms clean but not fancy (no TV... but you ARE on vacation). The staff was really awesome. Considering we spent days on end watching the Weather channel and waiting for the skies to clear, they took wonderful care of everyone despite the often-grumpy demeanor of the guests.
I intend to go back... had wanted to go this year, but it's not looking like the scheduling will come through for me.
J