I've never sewn on a Pfaff, so can't help there, but I do have the newer Juki TL2010Q and use it solely for piecing quilts... it's KILLER!
My Bernina 830 (much adored by me) is a dual feed machine like the Pfaff, and let me just say that the Juki is superior for piecing. I have tried so many machines, from the $10k Bernina to a vintage Singer 201-2 in my quest for the ultimate piecing machine, and the Juki wins, hands down. If my testimonial isn't enough, ask Sharon Schambers, since she's an award winning famous quilter, that's what she also uses! (She has the older TL98Q).
I have found the trick with the Juki is to sew with the presser foot pressure reduced to nearly zero, and it performs even better than the dual feed. Honest. It's amazing!