I have also bought a new to me 6600....I bought it last Friday and it is amazing.....I bought a Pfaff Select 3 about four months ago so had no intention of buying a new machine but my local machine shop had it for just over $800 (£500) and it just seemed such a bargain. ( trade in from someone who had bought the Horizon)
The only thing with it was it had two small scratches from where it had been in a cabinet....but I do gather they scratch really easy so intend to get a silicone cover for the base....have touched these up and it looks like new.
It is so quiet qnd smooth...stunning machine.