Best sewing machine for free-motion machine quilting

I am a machine quilter.  I want to know what people think about the Janome MC6600P for Machine Quilting.  I have a Viking Designer SE but it has draw-backs and I have been finally forced to concede that the Viking just isn't designed for machine quilting.  I need more throat space and there seem to be a lot out there that beat the 7.5 inches of the SE.  Thoughts?

I have the Viking Sapphire 850 that is an absolutely wonderful machine for quilting, although I did have to purchase the walking foot separately. The Sapphire 870 comes with it I think. I also purchased the spring action free motion/stippling foot for it.  And, it has a nice 10" harp. I've read mixed reviews about tension problems with it but I haven't had any problems whatsoever with it.  I have machine quilted and done FM with it and love it.  It has a lot of nice features.

I've been reading a lot of good things about the Janome MC6600P also.  So, yesterday I put one in the layaway. Hopefully, I'll have it home in a couple of months.  I have the cash for it but I didn't want to empty my bank account for it.  It cost me $1399, about the same as the Viking Sapphire 850.  I've read about tension issues with the Janome MC6600P also when doing free motion quilting, but my dealer said it is mostly user error. Machine set to too low a speed and user doing FM too fast.  Should be opposite.  I'm not too worried about it though because I don't do a lot of FM quilting.

So, I really can't comment on the Janome yet, since I haven't used it but maybe you will get some more responses to your post.  It is a gorgeous machine as is the Viking Sapphire.  I will warn you - the Viking feet are expensive.