I bought a Pfaff Quilt Expression 4.2 last August and I love it - upgraded from the Pfaff 7570. Besides the dual feed, the feature I like the most is that when you mash the foot pedal, the pressure foot goes down automatically - you do not have to lower it yourself (but there is a button to raise and lower it if you want to do it manually).
There is a great youtube video, over an hour, from a shop in California that will give you a great demo on this machine, showing all the great features. Check it out.
https://www.youtube.com/watch?v=uNHBEUtkUkI