I've had mine almost 3 years and love it, have had no problems whatsoever. It's a great machine for free motion, I've done queen size easily.
The 7700 soon to be available has slightly larger throat space at 11" and also is a free arm which the 6600 isn't, but I won't be changing as I am quite content with the 6600.
I can't comment on price as mine was bought in France - but if you do buy it, get the additional Accufeed feet - you wont regret it.