madcaster said:
But if I leave DR at christmas to go to Jamaica will they let me back in without any return flight? The more hassels I can avoid the better.
That's a good question. You have reason to be concerned.
You'll be buying your round-trip ticket in the DR, so you won't have to worry about a ticket clerk/agent in Jamaica telling you they aren't allowed to sell you a one-way ticket. I don't recall ever being asked by an official at the airport to show a ticket, but then as a resident I would have been in a different line than you will be. Someone else should be able to speak to that.
What you will have in your possession are a passport with the initial entry stamp and the exit stamp, and the stubs of a round-trip ticket that correspond with the date of the exit stamp.