Haven't done any quilting on the 6600 yet, but used a sandwich for practice FMQ and the walking foot. Didn't have a problem at all. I really love my machine, it is very user friendly. I did purchase the face plate for just the straight stitching though. It only has a small circular hole for the needle and I use it when I piece.
I can attest to the even feeding of the pieces. I went from a machine that I had for atleast 15 yrs and it wasn't purchased for quilting. This machine has made a TREMENDOUS difference in my abilities.