I had the 6600 and just traded it in for the Horizon (6700). If you can afford the price increase, I would definitely go with the Horizon. The additional features are great! - wider bed, 5 lights (I could sew without lights on in the room), more stitches, and one plate that converts from standard wide hole to single hole for those times when you want a single-hole plate (great feature - you don't have to change plates) - a tiny bit lighter than the 6600 - places on the machine to hold all your feet (and lots included - 3 feet for free-motion-quilting) - and the left side comes off so you can have a free arm for circular items like bags/slacks/etc. - those are just some of the highlights that impressed me and I am VERY happy with the machine!