I have the 7700 and love it for everything I've asked it to do. I'm doing my first FMQ now and am very satisfied. the only complaint I've seen is that its start up (when pressing the foot pedal) has a little hesitation. I've seen people selling theirs to upgrade to the new Janome 12000 so there might be some good deals out there on used machines.
Make sure to test drive whatever you're interested in. Good luck in making a decision.