Hammerheads though scary looking, usually dont attack people. In Hawaii-the big killer there is the Tiger and that one scares the you know what out of me the most as it will eat anything. Ive gotten into cages to go diving with Great Whites in Australia, but I wouldnt want to see a Tiger age or no cage! I still went diving in Hawaii though (did see several sharks). I say go for it, just be on the lookout. Seems that most attacks there are on surfers (and a few out swimming in the am and pm-prime feeding time)!
As for Labadee, I liked that stop too. Just be prepared in the shopping area for aggressive merchants who will follow you around (and a simple no thanks wasnt enough). I went in alone, but following a bunch of guys. My arm was grabbed a few times to pull me over to someones stall.