I have the 6600. Havent read the whole thread. Biggest thing I can tell you is that it is touchy to learn the auto-cutter...you need to make sure to load your next piece from the front so the "cut" bobbin thread goes back and not in because it will make nests. Second, the 3.5 setting for the quarter inch foot IS NOT a scant quarter but a full quarter....I had to re-set mine to 3.8 to get a scant quarter. I would strongly suggest a 1/4 inch walking foot as a future purchase.