Cornell, I believe, has a similar program structure. I interviewed at both programs and I had reservations about this system as there are significant pros and cons to it. However, I met a Tufts-NEMC medical student on the interview trail and he really loves it there.
That being said, I ranked Cornell highly and I didn't rank Tufts at all. Why the difference? I love Boston, but I don't think that Tufts would have really trained me as well as I would have liked. During your interview day (and even before/after), try to gauge the amount of patients that residents actually work-up on their own. I feel that, since Tufts doesn't have a prominent ED, the majority of patients admitted to the hospital were transferred from outpatient/sub-specialty clinics. In this context, much of the diagnostic thought-process had already been outlined, and I think that this is where the best training comes in as a resident.
But, then again, that's just me. However, I really liked the location, facilities, the faculty, and the other residents! The problem was my perception of training, and that was enough for me not to rank it. Maybe in restrospect, I should have (just for NRMP matching purposes), but what's done is done....
Hope that sheds light on the program for you.