I had been researching the same thing. I wasn't overly impressed with the 6600, did have a Viking Sapphire turn my head - but I already have a machine that has over 200 decorative stitches that I never use. I really considered what it was I was needing. For me the answer was a larger harp space and great straight stitch. Juki and Brother owners seem to love their straight stitch machines, by and large. I am going to go with the Brother PQ1500s. I was able to test drive one at a local dealer. However, their price is at least $300 above, depending on if they are running a sale or not, than what I can find online (both Amazon and AllBrands sell this same machine). I have searched the threads and the vast majority of people who have bought from AllBrands are very happy with their purchases and service. I like Amazon, but last I checked, their price was a little higher than AllBrands as well. I am also happy that the machine will be so straight forward, there really isn't a lot to go wrong with it. I anticipate it serving me well for many years! Price online from AllBrands - $599 plus free shipping, no tax.
Good luck in your search!