From my experience, the leap from 6600 to 7700 was huge. FMQ is a dream on the 7700 with consistent stitches, auto tension and the adjustable free motion feet. I've got a perfect 1/4" seam with the O2 foot and the auto single hole plate and I've never had to fiddle with tension at all. The extra 2" of throat space makes a huge difference. I can recommend the 7700.