I do believe your story. You applied to Duke early decision, got rejected, went regular decision and got in Emory and Tufts while being waitlisted/accepted at Vanderbilt.
I can sense you are going to be one of those students who spends their entire freshman year dreaming about transferring to the top of the Ivy League. Going to Vanderbilt does give you a decent advantage over anyone applying from outside the top 50, but the chances are still very much against you. Even people in the middle to lower Ivies are trying to get into the top 5, but many of them fail in the face of single digit transfer acceptance rates, most of which are 5% or lower.
Your chance of getting into a top medical school (and being competitive for any secure future) depends on your social networking, inherent talent, and hard work. The resources for you to succeed are there at Vanderbilt, as they are at many other universities. The professors at many schools can teach - the problem has to do with students being unable to learn. Any result you get on the MCAT is going to do more with your own motivation and ability, rather than how well your college could have prepared you. The same goes with work experience.
Thus, the question changes: Are you good enough for Vanderbilt?