I don't know about Tradewinds. But I can tell you this. Belize has different dive areas that vary. San Pedro is the diving hub with multiple dive shops, restaurants, night clubs. Dive sites are within a few miles or even half mile from the beach. You're right on the barrier reef out there, Caye Caulker is the same type of location but less people.
Down south you have a few scattered resorts and then Placencia. More quiet little town. Better access to the inland activities than San Pedro. Mayan Ruins, cave tubing etc. But these areas are 15-20 miles from the barrier reef. Good diving though.
Then you have the outer atholls. Pretty much eat, dive and sleep type resorts on isolated little islands of Turneffe, Glovers and Lighthouse reefs. There isn't anything to do but dive basically but that is where the best diving is.
Hope this helps.