Hi. I am an MS1 here. You are right about our final class size. I would have to say that the IS preference has more to do with the fact that in-state students are more likely to target this school as a top choice and likely put more effort into their applications etc. If given multiple offers (which a large majority of our matriculating class had), students are more likely to matriculate into a school in their state, and UM seems to be a desirable school. Florida has a lot of applicants to medical school but we also have a lot of medical schools, so a ton of us stay in state. I am not denying that there isn't any instate preference from the perspective of admissions (I honestly have no clue), but if this is a target school for you I encourage you to apply with your best application (I know this secondary is quite a beast).
If anyone has any questions about my experiences so far please let me know. Best of luck to everyone!