Ziplines are FUN!!!! I've done them in Puerto Vallarta, Roatan, Costa Rica and in the states. Haven't done it in Jamaica, though. Dunn's River Falls is my favorite place in Jamaica and I HAVE done that 3 times. Lovin' every minute of it!
I,too, tend to like using local companies rather than ship's tours. I've always had great results using recommendations on the boards for tour operators. Saves $$$ so I can do more of them.