At my interview at Stony Brook they told us the average MCAT of this year's first-years is a 32. I withdrew my interview at Downstate after I got accepted to SB, so I haven't actually visited the school, etc., But I know I would rather be on L.I. than in Brooklyn (but I would rather be in Manhattan than on L.I. of course). I've just heard that Downstate doesn't have the best facilities, and that the quality of education there is lower than at SB. Medicine at Downstate would probably be a little bit too raw for me, although that could be an upside for some people.
Stony Brook is prestigious allright but I got the feeling that most students just study there 24/7. A second year student told me that many of them are in labs upto 7 pm on certain days. I wonder where they get the time for reading outside of class.
Anyway, you might find this link interesting. It has their admissions data from
'94 - '04.