Just a suggestion - look at the new 710/750/780 series. If you can swing it I think you will be much happier in the long run. what is the advantage? Larger throat space (10" - just 2" shy of the new 830) even feed feet available (called IDT on Pfaffs ) sort of like a built in walking foot. Larger bobbin - holds about 70% more than the standard sewing machine bobbins, even more than the new 830!!!
Ask me how I know - I just came back from the Bernina store (they had a fabric sale today) and was looking at these. I have a 730 but think I will be selling it and going with either the 710 or 750.