We used to stay there several times a year, but there's no convincing reason to use the on-site dive op and some good reasons to use the independent ops that most members here favor, so we never went with Scuba Du.
One used to be able to go and have a drink or snack and do some swimming and snorkeling at their nice little beach and roped-off snorkeling area. We did that fairly frequently because it was peaceful and quiet and the food and drinks were good. We could rent a tank inexpensively at the dive hut right at the beach for an equipment check-out dive or just a low-stress long, shallow meandering shore dive. Unless you get fairly far from shore, currents are usually barely noticeable there.
More recently they wanted one to rent a room for an all-inclusive day rate or otherwise wouldn't permit use of the beach or facilities. It could make sense if one were coming off a cruise for the day, since the fee was in line with other inclusive beach clubs and it included a nice place to nap. We have an even nicer place to nap a short distance away but even showing them a Cozumel driving license wouldn't get them to budge. I sort of miss it.