Yes, we did the helmet dive in Cozumel in December, 2002. We were taking our teenagers after helmet diving in Bermuda. It was very disappointing as compared to Bermuda. You walked in a line holding hands and saw very little except for the underside of a pier. In Bermuda we saw reefs, fish, eels, and the dive master had signs he pointed to to tell us what we were seeing.
I do not think the Cozumel dive is worth the money. I also saw the dolphin encounter there and it was very commercial. We enjoyed the dolphins at Roartan in an environmentally friendly environment. Hope this helps!!