I have the Janome 6600, and since you mentioned that I'll tell you what I think about it. I LOVE IT!!! It has the larger bed for quilting and the built in walking foot. I would try it and consider it before spending that much $$$$ on anything. I do have a Babylock Dec Choice and I love that too, but it doesn't have the heavy duty feeling of the 6600. For that price you could also check out the Pfaff Expression line. They have a 10" bed and a built in walking foot also.
Good luck and Happy Shopping!!