When I was in college, there was a pediatrician (practicing for close to ten years at that time), came in to speak to us, and he was getting the MPH degree. He loved doing it as a physician because 1) he was coming from an entirely different perspective than the "young whippersnappers" (yes, he used those exact words) who were fresh out of undergrad with little experience, 2) he could do the degree slowly, and with no constraints, he had more time to enjoy the courses needed for the degree, and 3) he paid for school out of pocket, not having to worry about taking out extra loans to finance his education.
As far as financing is concerned, if you know that you want to go into public health, you can do a Preventive Medicine residency (check out this brochure for more info - it's great:
http://www.abms.org/Downloads/Which Med Spec.pdf). Getting the public health degree is a part of the residency, and I'm pretty sure that it is covered. Otherwise, I'm not sure that MPH programs will fully finance your master's degree (anyone else have any idea about this?).
Also, MPH degrees are things that can be done at just about any point in time during your MD training. I know people who have taken a year between the basic science and clinical years (helps alleviate the burnout factor), and also some people who have done it immediately after their rotations in third year, and also after fourth year (meaning that they applied for the match while pursuing the MPH).
There's a lot of flexibility in when you get the MPH. The best thing to do is talk to people who are doing the dual degree and get their opinion on what time may be best to pursue the degree - which will certainly differ for everyone. For me, getting the MPH and working prior to medical school was an optimal choice, but some people prefer to do otherwise. In addition, doing the degree during medical school may be easier on the pocket since you end up paying only for one year, versus doing a two year program (which would in actuality be much longer if you're going course by course in person or via the internet).
Best,
H&T
