what about an md/phd program? there are a lot of people working in biological applications of engineering and physics. systems biology and bioinformatics are two areas that immediately come to mind. this way, you can get the phd you want with a little extra baggage, namely the md. plus, you'll be guaranteed financial security with the md as you can practice medicine if you desire. i hear radiologists stack the g's too...
i don't think there's anything wrong with doing medicine for the money...just don't mention that in your interview. this guy says that most med students are in it for the money, anyway:
Med School Hell » Everybody’s In It For The Money
as for the type of learning in med school...well read this too:
Med School Hell » Medicine Is Simply Repetition
seems like med school and the practice of medicine = memorize + regurgitate + lather,rinse,repeat