Without knowing the cost difference between the two machines, I would choose the 7700 because of the 11" throat because that is what would matter to me Are they discontinuing the 6600? If they are, how long will parts be available? Can your dealer tell you the upgrades in the 7700 as far as the motor and the mechanical stuff, etc. not just the features? When I bought my last machine, DH helped decide on which model because it was more heavy duty, which was the newest model out. Not helping you decide much am I LOL. Good luck and BTW I'm green with envy :-)
Suzy