Acetabulum --
I am a carrib student and I tried transferring into a US school after my MSII year. I had pretty good grades and my Step I was 240/97. I didn't get in straight from undergrad though my MCAT was 11,12,11 (my GPA was around a 3.0 -- I double majored in English and Bio in less than 4 years and thought med schools would look at this as a reason for my low GPA, but they didn't really care). I am from Cali too, which makes it more difficult to get into a US med school out of undergrad vs. other states. In any case, I pretty much called every single med school in the US and asked them if they were accepting transfers. I can tell you that unless you have an "in" -- i.e. you know somebody that can push for you or have some extenuating circumstances -- you'll be hard-pressed to find a spot.
I got an interview an George Washington University, which I thought went pretty well, but unfortunately I was the last one out of the short list to get in. One of my classmates, a good friend of mine and with lower Step I scores, was the only IMG to get in, and he had to repeat his 2nd year. He had managed a 4.0 in his first two years, was from the DC area, and had suffered incredible family loss during his first two years of med school. How he was able to finish those two years, let alone do so well, is beyond me. What I am trying to say is that he was as hard-luck a case as exists, and he was a solid applicant -- even with all this, he barely got in.
Having said that, I know two other students in my class that got into MCP-Hahnemann after their MSII year. They had significantly lower board scores than I did (though they were both 4.0 students), didn't have stellar undergrad performances by any means, but had connections into MCP. And for MCP, you have to take your Step I early (by the traditional August/September med school start date standard) to apply for a position.
My point with all this is that it is possible, but very difficult, and you really need a solid "in". If you are seriously considering, you really should ask yourself a couple of questions:
1) Why do I really want to transfer? By no means is an education at Harvard necessarily better than an education at St. George's, but enough people feel that the person that didn't get into Harvard (or any US med school) is less worthy to be a doctor than the one that swallowed his or her pride and went abroad for the MD. I think it is obvious this isn't true, and if you talk to most people they will repeat the sentiment, but there is a discrepancy between what people openly say and how PD's decide who gets an interview at their residency spot and who doesn't. If you want a top-flight residency, you will need to get into a US med school. There are stories about every kind of FMG/IMG getting into every specialty there is out there, but no stories about an FMG/IMG getting into Hopkins or Brigham. You have to decide how much the reputation of the residency matters to you. If it is the stigma you wish to avoid, I would ask you if the myth you are trying to avoid be stereotyped into is being perpetuated by your desire to get out "at all costs." Just a thought.
2) Are you willing to do the things necessary to transfer? I don't mean to sound like Connery in The Untouchables, but it takes a lot of effort and a lot of legwork to transfer from abroad to US, and you are competing against a very good and very determined applicant pool. Believe me, I know. And for all your effort, the best you may get is a spot to repeat your 2nd year.
I don't mean to deter you -- in fact, I hope that this at least encourages you that it does happen, and often enough that I have run into people that have done it. But I will say this -- if you are going to transfer, go into med school with that mentality and do everything you can during your years there to do it. Chicago Med and MCP-Hahnemann take transfers into their second year as well (a fact I found out too late). Also, last I checked Brown had a program for Rhode Island residents who are abroad to transfer in, but you need to apply for it in something like October of the year before you wish to transfer. For IMG's: Indiana University offers transfers to Indiana residents; University of Wisconsin offers transfers to Wisconsin residents; Robert Wood Johnson offers transfers to New Jersey residents; Marshall offers transfers to West Virginia residents first, then Virginia and adjoining state residents. Tulane, Chicago Med, MCP Hahnemann, George Washington University, U of Vermont and SUNY Syracuse (Upstate) all accept transfers depending on space.
If I were to do it again, I would pick a state going in where I thought there would be a decent chance of getting in w/residence, and I would somehow get a driver's license or something else from there to start, and then get to know as many people as possible in the admissions department PERSONALLY. Yeah, that means (as kindly as possible) bug the living crap out of them until they know your grandmother's maiden name.
I hope this all has helped. I wish someone told me all this before I went into med school in the carribean. Good luck -- my experience has been that those people that have tried to transfer, even if they failed to get into a US med school, have one way or another ended up where they wanted to be eventually. I hope that inspires and assures.