I attended St. Matthews when it was in Belize, and I'm still working on the St. Joseph's program. I don't know much about how things are working in the Caymans.
If you do the MD/MHSA program, you spend the first three semesters on the island, then you go to Maine for the next two. You attend both SMU and St. Joe's classes. (St. Joe's has a very nice campus.) When you are in clinicals, you continue St. Joe's classes through distance learning or online classes.
A large number of Ross students transferred to St. Matthews, now in Grand Cayman, to begin study this semester. So far, the feedback I've heard from them has been great. It is my impression that St. Matthew's is an "up and coming" program that may prove to be one of the better Caribbean schools. Certainly with the large influx of Ross students (about 100 or so), they will have a lot more money to improve their program. Also, the cost is substantially less than Ross and SGU, the only other smart choices if you decide to come to the Caribbean.