I had the 6600 for about 3 months, and wasn't all that impressed. The Acufeed thing is great, but when piecing the fabric went right down into the hole. You couldn't use a single hole plate on it with a regular 1/4 foot because they don't make one. They only make a single stitch plate to go with the Acufeed 1/4 foot which isn't really a single stitch plate because the needle has to be at 5.5 to use the Acufeed 1/4 foot and the plate looks very similar to a regular zigzag plate, so I got the Horizon, so far so good, it comes with a convertible stitch plate that I can use with my regular 1/4 foot and the fabric doesn't get stuck in the hole.