While I can't comment from the perspective of an adcom... medical schools train people to become radiologists (non-interventional) and pathologists (including forensic). Personally, I see no reason why someone looking to embark on either of these career paths that are extremely valued in medicine would benefit on the pre-med side from following around an FM doc any more than getting experience with a forensic pathologist would be important for someone hoping to pursue peds (remember that all med students will have to work with deceased patients as well as those still alive).
My vote is, if you want to do mostly research with your MD, have most of your experiences be research, if forensic pathology is what you want to do, work with one, family medicine? volunteer in a fam med clinic.