Hi CC!
I live in Atlanta and have been using the airport for years....and use Delta mostly for Mo'bay as its our main airline hub here and we get great pricing. The airport is HUGE and as you know, 45 minutes isnt a lot of time and its hard to say if its enough and is dependent on what terminal and gate you are are arriving and departing from. Your next flight should pretty much start boarding when you land and the doors shut 10 minutes prior to departure so....unless I'm mistaken.... you really only have about 35 minutes.

The only time my luggage did not make it to Jamaica was the only time I flew Air Tran down. It arrived the next day and was delivered to my hotel. I now bring a few necessities in my carry on in case this happens again.