My actual score was 2 pts higher than my highest scoring Kaplan full-length. It felt good.
I think it a reasonable approximation of what your actual score will be, I will tell you that my consistent lowest score w/the Kap full lengths was my highest on the actual exam.
Incidentally, I was just hired as an MCAT instructor for Kaplan and there's something I noted. Kaplan's pretty good about a preference for MCAT instructors who took the MCAT, whereas TPR accepts MCAT instructors who haven't (grad students in the sciences etc.) This is strictly my anecdote I work in a lab and a lot of grad students have been receiving EMs about teaching for TPR. Personally, I wanted an instructor who had taken the test. It's a lot more than knowing the science, it's knowing how to deal w/the test which only a MCAT taker could really speak to.
But spacecadet's reason is a good one: If it's closer, chances are you'll go there more often, spend more time there, and get more studying done=Higher score