I upgraded last year from the Janome 6600 and still think it's a wonderful machine.
You are bound to like it ... though I am not familiar with your current machine or the Pfaff machine you mentioned.
If you are considering the 6600, it is an older model ... I would highly recommend you look at their more recently released 8200. From what I understand it is the updated version of the 6600 with some great improvements.