Another consideration is the speed the storm is moving. Right now it is creeping along at about 10 mph. By the time it reaches the islands late Sunday and Monday it is projected to be traveling about 20 mph. This, along with the relatively small size of the storm and the projected distance from SXM when it passes to the south, should lessen the potential impacts considerably.
In 2012, we arrived in the early afternoon on Saturday just before TS Rafael passed over the island later that night. It was a large storm and we had 40-50 mph winds, lots of rain, and high surf through early Monday. We were at La Vista on the beach but had no loss of water or power. By Tuesday things were much better and there were few problems (roads and other infrastructure) on the island in the aftermath of the storm.
If you decide to go ahead with your plans I think you stand a good chance of having a decent trip in spite of the storm.
Good luck!