I have been traveling a lot for the last year and haven't been home to drink much of my beer, so I have been doing this without any serious issue. I didn't add quite so much extra pressure when I was disconnecting the CO2, but I wouldn't expect that to cause problems.
In my experience it does not keep it especially fresh. Right now in my keg I've got a nice spring ale, that was definitely better when it was fresh a couple months ago. That was a recipe that I knew was going to be better fresh, and it's still quite drinkable -I expect to finish it this weekend. I don't know if it would age more or less than in a bottle, but don't expect it to be in perfect stasis while you leave it.