Well I got the hd850 today and so far I'm not liking the experience. See... The hd850 and hd950 only output upconverted signals through their HDMI interface, but this can be changed via a small hack that you can find easily on the net.
But in my case... when I did the hack and changed the resolution to 1080i the TV just started flickering... It's odd though, because when in 720p or 756p the screen just stays blue, whereas in 1080i it "tries" to display the picture. I'm trying to solve this now and I if I can I'll tell how...