Key Dives in Islamorada is great. In fact, that's where I got my AOW card this past November. We showed up without our medical clearances and they really went the extra mile faxing our family doctor to get the forms and everything turned out fine. Actually, their service is better than the "Carribean" service. They will hang your wetsuit up to dry for the next day. They are great to dive with especially if you plan on diving for a few days.
I just returned from Cozumel and we had to drag our gear off the boat, rinse it and store it ourselves in a locker and drag it all back onto the boat again. So, I don't know where this "Carribean" service is in the Carribean, but from my experience it's not in Cozumel. So, you'll actually get better service at Key Divers (if you are AOW dive the Eagle, there is a monster of a Goliath Grouper living there). Enjoy you're dives.