Purchased my 6600 June 8 2008. the only thing I have ever had done is regular cleanings. Still going strong. I know nothing about Pfaff's but I think the extra feet, bobbins, accessories, etc. are more expensive than the Janome's. I have purchased a lot of extra "specialty" type feet for my 6600 and they are not expensive at all. Maybe looking into the accessory costs for all the machines you are considering will help in your decision.
Just something to consider....