My biggest thing to think about with the snorkeling and biking is...
How much time are you going to be out for those activities? Renting that equipment individually is infinitely less expensive than a cabana. If you’re going to be out doing stuff most of the day, that is a LOT of money to pay for someplace to put your bag.
We had one - my parents and I - in Feb and it was a godsend for us because my dad was awaiting hip replacement surgery so having the golf cart to and from was essential for him. I doubt we would have been on the island long at all without that. But outside of that, we didn’t find it something necessary to enjoy the island - and we DID stay at it most of the day.