David,
I can't answer your question specifically, but I've taken Delta many times, and will be taking them again in December.
All I can tell you is that since their merger with NorthWest, they claim they will be expanding some (?) routes.
All of Delta's flights to the DR out of BOS stop in ATL, but perhaps they have (or will have) some direct flights from other airports. The FAA determines which airports, and which airlines, are allowed to offer direct flights to any specific country. And I imagine Homeland security has some say in the matter, as well.
By the way, if you can figure out how Delta works their Skymiles I'd like you to explain it to me. Do you have "Y", "Z", or "B" miles to use?