We also have the Pfaff Hobby GQ 1200 with Qbot, stitch regulator, and Imperial frame. We have had some tension issues, but when we got through those we have been very pleased with the results on our machine. We have quilted 14 quilts so far; 12 lap size and 2 queen. The stitches are beautiful and consistent in length.
I have learned to be diligent about cleaning the lint out of EVERYTHING: bobbin case, bobbin area, needle area, tension disks, and as much of the innards of the machine as I can reach with a pipe cleaner. Any tiny spec of lint in the wrong place can drive you to say things you don't want anyone else hearing.
PM me if you have any specific questions. I am by no means an expert, but I'll be glad to help if I can.
Darren