I don't know anything about the pilot-physician program beyond it's existence, but I am fairly confident it will not help you get a fighter - that's still merit-based in UPT on AD. The best "guarantee" for a fighter is getting hired by an ARC unit that flies fighters.
The AD, regardless of job type, is generally the antithesis of stability. Your alternative of part time ARC pilot and civ doc will likely be far more stable than anything AD will offer. Additionally, if you go pilot physician on AD, my bet is you do not get to "see the world" (at least any good parts); that's such a specialized position that I'm guessing there are only a few spots at very specific locations. Pilot physicians are not a normal position at any "standard" flying base. Additionally I'd look heavily into the program and what it entails long term - do you stay on a relatively normal flying track or do you do one assignment and then off to Walter Reed for you? Bottom line is the last time I heard of a pilot physician in the Viper world, it was 10 years ago and they had done one assignment as a pilot/flight doc, then went onto some medical-only assignment. Do your research, it may not be exactly what you want long term.
There is pretty much no limit to what you can possibly do in the world with ARC vs. AD. There are ARC personnel working green door projects, at DARPA, doing 3 year assignments in Europe, working at AOCs, flying test, shooting ISIS in the face, fucking up travel vouchers, and torturing dental patients. The ARC "one weekend a month/2 weeks a year" is not the baseline these days for a lot of people...if you want to do more than that (and you have to has a pilot), there are limitless opportunities.