Regarding making connections... At Sackler you do your core rotations in Israel but you also spend several months in America where you can do rotations and electives at hospitals with residency programs that you are interested in. This give you a chance to not only know get to know the hospital, but to also get LOR from US doctors. After looking over the match results from Sackler (you can search for last year's on this forum) and SGU, I don't see any difference in regards to which fields people match too. The biggest difference is that most Sacklers go to programs in the North East or California, so if you had your heart set on going to the mid-west you may have a tougher time.
I got pretty good scores in the USMLE's but i didn't match with a residency program this year, bec. i missed this part( CONNECTIONS ), i know the FMG do bad in the match process , but the caribben graduates do multiple steps better.
While not matching anywhere is a problem for FMGs as a whole, it is not a problem for the big 3 Carib schools or any of the Israeli schools (well, I'm sure its happened at some point, but it is very rare).
Whatever specialty you gonna chose after your graduation from med. school, you will get it even if it is a highly competitive specialty, if you got good scores in the USMLE + STRONG letters of recommendations from U.S. based doctors you rounded with them during your clinical rotation.
Not exactly true... unfortunately, no matter what you do there will always be a stigma attached to being an FMG. Coming from SGU or Sackler helps, as they have good reps among program directors, but you wont get a derm residency just by virtue of having a high USMLE and a LOR from a U.S. Doc. If that is all you needed then Ross and SGU would be cranking out plastic surgeons and dermatologists. Instead out of a class of ~200, 1 or 2 end up in a super-competative field, they are exceptions to the rule and probably have some extra connections or an incredible CV.
The short answer to your origional question is NO, there is no overall benefit to going to one school over the other. The long answer is that it depends on exactly where you want to end up for residency and where will you be the happiest.
Hope this helps.