Oh, I thought you were planning to do a lot of diving. If you're only planning to dive 1 day, Coz would be worth it but like Marg said, with you limited experience, PDC would be just as well off. I find it funny that TA folks was saying to avoid it, then again, I think when it comes to reviews/recommendations diving related, TA is downright hilarious! PDC diving is great and for 5 days but 1 day especially, it will not disappoint. Just looks at all the dive ops there... if it really sucked, they wouldn't be in business. Also, south of Tulum is some of the most pristine, unspoiled diving Mexico has to offer in Costa Maya and Mahahaul. I've never gone because I don't like the logistics of getting there but it's definitely on my bucket list.