This all situation with EX is rare.
Now they hired TRANSMERIDIAN AIRLINES' 727 for Las Americas-SJU daily service. The plane is based in SDQ.
Actually I don't see in Amadeus their HEX SJU flights, what happened to them?
I used to work with EX when it all started, when UX's representative Mr. Antonio Mota started to fly regular flights to Barahona, Santiago and La Romana, it was very funny. Since 1998 they wanted to fly to SJU, Air Europa had no available 737, so they stopped. Then EX merged with SAP. By the way, they have a nice web now, check this :
http://www.airsantodomingo.com.do/
Meng should check this web, such a small airline like EX has a better web then so well promoted on this forum BQ
The only bad thing about EX is their baggage allowance, it is 20 kgs only

But they have frequent flyer program.