I recently graduated from Michigan State College of Osteopathic Medicine. This debate over whether to become an MD or a DO is not as significant as you would think. You should base your decision on location, personal preference (personal interactions with current students and staff), and philosophy. For instance, MSUCOM has devoted itself to serving the community and building upon the philosophy of mentorship throughout our training. Incoming students are given peer mentors to "usher" them through the initial adjustments of medical school.
In the end, if you are a smart, hard-working medical student you're going to get a good residency MD or DO affiliated. As a strong DO student I was highly esteemed for my clinical abilities and knowledge base at two reputable MD emergency medicine residencies (Regions in St. Paul and Spectrum Health in Grand Rapids, MI). Sure, if you go to a "Ivy League" MD med school you'll have better name recognition, but most MD med schools do not have an automatic name affiliation with suspected educational quality.
Just starting my first year out of medical school, I could not be prouder of being a physician. I am proud to be a DO! In the end, the nurses, patients, and fellow physicians respect you for the quality of your work and reputation with people not by the initials behind your name.
P.S. In many ways, DO students are very competitive since their clinical rotations seem to demand more clinical performance earlier than MD counterparts...this seems true in my limited comparison with students from other schools.
Matt Flannigan, D.O.
P.S. If you do well on the COMLEX (osteopathic boards) you'll still be competitive for MD residencies, regardless of whether you decide to take the USMLE. COMLEX tends to be highly clinically based.