What tangible difference does it make by going to a mid-tier to top-tier residency program instead of a low-tier?
When said and done, if you don't want to set a foot in the world of academia, your employer only cares if you are board certified or not correct? Granted, I'm sure you will earn a lot more working as a hospitalist at MGH compared to some place like Kaiser... (is it?) I'm sure you'll obviously get better training experience also...
So in the end, as a person trying to become a M-F hospitalist working at some local (mid-sized) hospital, will it impact me much by going DO? By not getting residency at a university hospital?
For one, you get paid less in academia, about 1/4 to 1/2 less than private work. Moreover, in general, the pay is inversely related to the prestige of the instituition, so Ivy league hospitals tend to pay like crap, like 120k/year for a hospialist.
Going to a mid/upper tier program will provide you with, in all likelihood, a better education, more fellowship opportunities and increased employment opportunities. The most important thing, at least for someone who is only interested in becoming a hospitialist, is probably education. Some "low tier" community programs are completely fine in regards to education. Christiana in Delaware, for example, is a 900 bed hospital with numerous fellowship opportunities. I'd imagine that the training there is more than sufficient. On the other hand, there are other community internal medicine residencies at hospitals with only 150 beds and no in house fellowships, which makes me suspicious of the residents' education.
Being a DO will not matter for most jobs. Some elite private groups and academic hospitals will not hire you solely because of your degree. These exclusionary groups are a small minority, however. Other institutions may potentially not hire you if you are only AOA board certified opposed to Acgme board certified. Once again, these employers are a minority, but probably more common than those who will simply not take any DOs.
Being a DO does not exclude you from training at a mid/upper tier program. I would agree that matching at an upper tier internal medicine program is probably significantly more difficult for a DO than a USMD, but matching at a solid mid-tier university program is probably only slightly more difficult and, in some cases, exactly the same as a US-MD.
Nevertheless, if you are content with training at a community based internal medicine residency program and practicing at a local community hospital, working 2 weeks on and 2 weeks off, and getting paid in the low $200s, you should have zero problems as a DO.
I'm not sure if you're a pre-med or not, but your interests may change when you start medical school, so just to give you a heads up on the opportunities as a DO:
If you do anesthesia, PM&R, family medicine, pyschiatry or pathology, it is realistic, if you deserve it, to match at an upper tier acgme program.
If you do internal medicine, Ob/gyn, peds, radiology, or general surgery, it's realistic to match at a middle tier acgme program. Probably lower tier for general surgery and (maybe) radiology, however.
It is unrealistic, as a DO, to match at any Acgme neurosurgery, orthopedic, urology, ENT, derm, plastics, rad/onc and (maybe) opthamology. I'm not saying DOs cannot match into these residencies, it's just unlikely.
If you decide on doing surgery, AOA general surgery and AOA orthopedic surgery are abundant. However, there are very few (20 spots of less per year) for AOA neurosurgery, ENT, urology, and eyes.