Just returned from diving with Club Cantamar and I found it a mixed lot. I stayed on site with them. Rooms were basic and clean. That's all I look for in dive lodging. It is most certainy NOT a resort.
Food - Not a stong point. I found it poorly prepared for the most part on land but the lunches on the boats were very good. Perhaps the captains, Jorje in particular, could help out the restaurant staff?? The club is a good 15-20 minutes from La Paz. There is a shuttle that will take you into town in the evenings, but that sets your schedule as well. There is good food available in La Paz, but watch your pockets. The hands in them may not be yours.
The boats were large and reasonably fast. The water was fairly flat, so motion was not an issue. The few times there was some wave action, the boats did move but there were no cases of calling for cars. They seat divers side by side, one tank right next to the other. This is much different from the usual every other tank you may be used to. It makes for a very crowded gearing up time. CF is the term you most often heard with regards to that. They will put 25 - 30 divers on the boat which can lead to a better understanding of the term "cattle boat", although they let you dive your dive with no real limitations.
The Captains were good and very capable; the dive masters were uneven . One, Chu Cho (sp) was very capable and took care of the 25+ divers on the boat. Others were barely competent. They might - or might not - hand you your camera, return your gear to the proper place, rinse camera, and so on. I can, and usually do, take care of my stuff after a dive, but it's nice to know what to expect. No soup for them.
Diving - Not great vis, sometimes down to 20-30 ft. This is, as always the function of weather and I have seen it much better. Luck of the draw. No whale sharks or hammer heads but did have 2 surface encounters with fin whales which was super neat. The sea lions kick ass. Be ready to change your dive plan as the current can come up and can be very tough to swim in. Some very good sized schools of fish, nice diversity, not a lot of coral and certainly different than Caribbean diving.
As for La Paz vs. Cozumel...I'd tell most folks to go Cozumel. Much better vis and San Miguel is a great town to walk around in with good eats. Not as inexpensive as it once was (cruise ships, you know). I have been in the Sea of Cortez before on the Salomar 5 before it changed owners but I doubt I'll go back a 3rd time. Lotsa ocean and so little time.
I have an album of photos posted here as well. click on photos at left and you can see what I found that caught my eye diving there.