6-8 days a month would be well worth it to fly fighters, in my opinion. And, while I'm a long way from making a decision, 3 years full-time service doesn't seem all that bad. It's not like I'll be making any less money than I am now as a grad student ($23K/year hurts, lol).
My end goal is not to get into the airlines.
If I have my way, one of two things will happen:
1. If the Air Force gig really works out great, I might try to go full time, and then apply to test pilot school, and if I'm really a rockstar there, astronaut training. (Hey, I can daydream, right?)
Alternately,
2. After I finish my degree, I'll take 2-3 years to go to OTS, UPT, and the works, and then afterwards get my civilian career going whilst putting in the necessary time with my squadron too. If I take a research fellowship-type position here at GA Tech, then I shouldn't have too much trouble making time for both. After my 10 years is up, I'll let the Air Force thing go, and really put 100% into my civilian career.
Also: Quasi-related question. I was told that 10 years reserve duty is the minimum for a Air Force Reserve pilot. Does the 10 years start as soon as I go full time (e.g. when I start OTS), or does the 10 year countdown begin after I finish UPT?