I totally disagree with you saying that a GPR only teaches you to treat hospital patients. Now granted, I'm an oral surgery resident, but my girlfriend did an intense hospital GPR residency 4 years ago and has been in PRIVATE PRACTICE SINCE, and most of my friends have chosen and done GPR's over AEGD's.
You don't do a GPR only based on the fact you want to do hospital dentistry. You do a GPR in order to be exposed to the broader and MUCH MORE IMPORTANT aspects of your degree/training. Now, some GPR's (VA's or private hospitals) may offer more advanced prosthodontic training or endo training) while many inner-city/public hospitals may be a completely different ball-game...
Almost everyone who does a GPR goes into private practice. But what you've gained in that year seperates the big boys/gals from the AEGD residents and the fresh grads.
Choose your program wisely. I know GPR programs where the residents placed and restored over 60 implants in 1 year. I know other GPR programs where the residents extracted over 3000 teeth. You've got to look for a happy balance. One that will teach you to deal with medical emergencies in your office, expose you to dealing with other health-care professionals on a regular basis (because you are part of the team), teach you to perform advanced dentistry (which you will have to continue learning through the life of your career anyway), and how to make the right decisions in your patient's care.
Regardless if you choose an AEGD or a GPR in the end doesn't matter too much though. At least you are thinking about it and you can see that there just isn't enough time to learn everything in dental school.