I have a Pfaff QE4, almost identical to your machine. I only ever use Schmetz needles and have never had an issue with thread breaking unless my tension was the problem. My Pfaff dealer only sells Schmetz needles so I'm a bit sceptical about the reason given to you. One thing that I have found important is to place my thread spool in the correct position while sewing i.e. cross wound spools like Aurifil should be in the horizontal position whereas straight wound spools should be vertical to accommodate easier feeding. (not sure if my terminology is correct - sorry). Maybe if your'e quilting use a topstitch needle that has a bigger eye or a larger size needle could help. Good luck, I hope you resolve the problem.