I think a big thing that no one touched on is that DOs are very actively recruited into MD residencies by MDs themselves. I've seen it happen more times that I can count, at least in NY. DO residency slots, since they are fewer in number and have a great demand than supply, dont have to work as hard to find residents. Granted, we may not being talking neurosurg at harvard, but most of the programs that 99% of us will be applying to all have the same challenges in todays healthcare climate.... they need to fill their spots to pay the bills. In NY, the feds pay a hospital more than $120,000 a year per resident. The hospital kicks back 40k to the resident, buys some insurance for him/her, and they bank a cool 60K, for doing nothing, plus they save the hospital cash by being able to send the attending home, hence they probably make much, much more in the billing the resident brings into the hospital. It only makes sense to fill your spots and fill them early.
My point is, MD programs, regardless of their quality, perceived or actual, know when they see a good doctor. When so, they recruit. DO programs dont do this as much, hence they lose students, often not because the MD program was better, it was because the DO student was made to feel by that program that they were wanted. If you think this isnt true, wait till you experience it.