I just purchased a 6600 about a month ago and love it!!! It is sooo user friendly and I love what I can do with it compared to the one that's being, sort of, retired (won't give it up). I paid $1149 for mine and it was a great deal!! If you purchase through a dealer, then you usually have a year to upgrade your purchase. They'll take what you paid for your machine and put it towards the new one.
The new Horizon looks to be a beautiful machine, but is going to run about 800-900 more.
I don't have the 350, but the next machine I look at is going to be an embroidery.
Hope your dealer is as nice as mine!!! Good Luck!! :-D