Welcome to the board!!
What is it you don't like about the Janome 6600 for quilting? This is what I'm currently using. Sure ... I would love a larger harp area (the Horizon 7700 has a larger area than the 6600), but someone on the board here posted that she quilted a KING with a 6600 recently. I've quilted a Queen and am currently quilting a large landscape lap throw with lots and lots of quilting on it.