Good question! We are in the middle of a very exciting time for Direct Primary Care. Both family medicine and internal medicine are good choices for outpatient direct care practices. We are very lucky to have the doctors from Atlas MD post frequently here in the family medicine section of SDN. I have been interested in DPC for a couple years now and I think that family medicine is in the best position to do direct care medicine. For starters, family medicine residencies have the most outpatient experience and training, even when compared to a primary care track IM residency. Nothing can compete with the level of outpatient training you will get in FM, and combined with the fact that you can offer your services for children and OB, you are way more marketable to the general public than an IM doc. It is very realistic to open direct care straight out of residency if you are motivated and are moderately business savvy. I'm sure Atlas MD will post in this thread, and you can search the post history for AtlasMD on this forum and you can hear about their story and how they opened up their practice straight out of residency.
