The vast majority of UMKC's class came in straight out of high school for a 6 year combined BA/MD program. Like Depakote said, you'll just be making up for any attrition. Thus stats for those who get in the backdoor might be hard to track down and verify. Having grown up in KC, I'd second the words of caution.
Unlike you, your future classmates will not have taken the MCAT. Sure, we pre-meds complain about it, but making it through the brutal prep and succeeding are somewhat of a rite of passage and certainly a badge of honor. Due to the accelerated nature of the program, your potential classmates will not have had much, if any, time to develop any outside academic interests. They will be younger, less worldly, and likely one-dimensional. It's a very clositered atmosphere.
Sure, Kansas City is spurring on local biotech developments (mainly at the Stowers Institute), but UMKC itself is not exactly the most respected institution in the state. KU-Med from across the state line claims this title in KC, with Univ. of Missouri-Columbia and certainly WashU in St. Louis taking the spotlight and funding for the rest of the state.
I would strongly urge you to apply elsewhere unless you will be a senior in high school next fall. Even then, go get a traditional Bachelor's, see where life takes you, and then apply. There's a reason why most medical schools delay enrollment until your twenties.