Actually if I had one it would be the 820 but as it isn't out yet. I don't 'need' it. I have two 440s and a 1260 (and a couple of others not in use) which I use in succession. (One on the sewing table, one on the floor ready to go and one in the workshop) I only need the 3 because I do such heavy quilting. My big quilts have up to 13,000yds of thread, so I really hammer my machines.
I was told for heavy users like myself I need only have it serviced every 3rd time the service warning comes up which would be a third less often than my 440s need servicing. Perhaps once a year for me, which would be really good though how I'd ever lift it down off the table and get it to the car heaven alone knows.
And all this is hypothetical as I don't have that sort of money to spend on a machine anyway. :)