Packamylase,
KCUMB was awesome for the first two years just like you have been told. I was STUPID and did not take the core site match seriously. I honestly did not realize that there would be such a disparity between core sites. I had the worst experience in Mobile, AL and then went up to Kettering, OH Grandview core site and realized what I had been missing. It was great and I regret not going to an established CORE site from the beginning. I have since done multiple rotations in California and had no problem keeping up with the big university trained students. I might even end up at UCDavis or OHSU for IM. As previously stated, if you work hard, study, and go to a great core then you will have an excellent education.
Words of advice: 1. Don't blow off path, you will be a superstar if you really study and go to all of ERF's lectures. I think that was definitely a strength of our school. 2.Get involved early in extracurricular activities so that you will have a cake time filling out your residency app/CV. 3.Start making your CV early and add to it every few months so that you won't forget anything you do and it will be easy to compile as a fourth year. 4.Take the USMLE, it will keep all of your doors open. 5. Don't take a month off to study for step 2, just study during a light rotation and get out of school early. I wish I had done that because I have to go to school all the way through april.
Good luck and enjoy the first two years and all the friends that will make!!