Can you tell me how far or how long can you quilt with l bobbin? My machine has a concave bobbin and it only holds enough thread to do a 12 x 14 practice quilt. I went to a class on fmq and there were 2 other woman there, I had to change bobbins 5 times to their one bobbin. It was a real pain. That is one of the main reasons I am thinking of upgrading, otherwise I have never had a problem with my machine. Viking definitely screw up with the bobbin on the #1+.