If you are looking into schools in the Carribean...I would definitely recommend St. George's over Ross. I have a friend who goes to St. George's and a cousin at Ross, I also work with a lot of residents and docs who are Carribean grads. First, I think that St. George's has a better rep. and about 10% of there students transfer to US schools for their third year. And if you do very well on the boards and are in the top 5-10% of your class you can get a competative residency. Second, from what I hear Grenada is a nicer island than Dominica, but that is a matter of opinion. At both schools you come back the US for 3rd and 4th year rotations- in which you are rotating in many of the same hospitals with US med students. And many of the profs at least at SGU are visiting profs from US med schools.
I think that throughout this you should keep in mind that these schools should really be pursued after applying to US schools. They are not vacation spots where you will be doing some work and then relaxing on the beach in the afternoon. In some ways they are more competative than US schools once you get in because they weed out/decelerate/fail a bunch of their class (at least I know that this is true for SGU). I think that they also determine who can take the boards...if you don't meet a certain cut-off they do not sponsor you, but I am not totally sure about this.
If you think you are at the point of considering these schools I would read up on them and see if they have an informational session in your area, I know that they both have some in the US. Good Luck with your decision and please don't let narrow minded people who automatically discount any of these drs as "inferior" convince you to give up on your dream.
I have worked with bad Drs. from some of the top schools in the country and wonderful drs. from Carribean and foreign schools. I think it really comes down to what you put into your education and what kind of person that you are. You will learn the exact same material as students in US schools, from the same textbooks, take the same boards and get clinical training in US hospitals.
If you have any other questions that I can answer just send me a PM.