Thanks for all the helpful comments about the Janome machines. I also found this discussion on Quilting About which was highly favorable. I drove down to one regional dealer today and tried out the 6600. She does not have the 6500 because she says the improved new acufeed (the only real difference) doesn't add enough to the price to make the lower price for the other model that attractive. Maybe. I thought the acufeed made changing feet a bit awkward because it's bulky and in the way. The Quilting About discussion mentioned this too, but apparently you get used to it. Other than that I liked the machine, and the lady was extremely helpful, and had a good price package, including a table.
She also showed me a Baby Lock Espire, which has some interesting features, but seems to violate the KISS principle (Keep It Simple Stupid). It has a jillion stitches because if they make a minuscule change to a stitch, like whether it locks at the beginning, they call it a new stitch. But the way it goes sideways and on the diagonal allowing lots of large decorative stitches is pretty tempting. As the saleslady pointed out, you could actually quilt a border design using one stitch, or combining it with others. Would I do this? I'm always bored watching the machine do something slowly like that.
Tomorrow I will go to another nearby shop and see if they have the Janome 6500 just to make a comparison, but I'm pretty sold, and this is a shop that many quilting friends highly recommend.