I have the Janome 6500P instead. I'm told the only thing that is really different is the walking foot on mine has to be put on by hand instead of being built in. I paid over $1600 for mine and it has more stitches that I will never ever use. Probably the 6600P is the same way. Really look at the machine and evaluate all the stitches available. Would you really use them? Test the numerous quilting and utility stitches....the are actually quite small, so would you use them?
I ordered my machine on line and wish I had gone to a Janome store to see it before plunking down that much money.