Well I can only speak for the 6500 which I have, I love it. I do wish that it had a couple more of the decorative stitches available on the 6600 but didn't want to pay the extra for just that. I was also financially not comfortable with going for the 6600. At the time I bought the 6500 I didn't know about the acue feed and it wouldn't mattered anyway, like I said, I was topping my budget with the 6500.
Yes, I would love to have the new Horizon, but I don't NEED it, and wanting it isn't worth the $ to me. Now maybe if I won the lottery...
warm quilt hugs, sue in CA