Yeah, the i850 keeps looking better and better. I'm completely replacing my system around Christmas, and I think this will be the new printer.
The S820 is a really great photo printer. But since it doesn't switch resolutions between photo and text printing, printing text is slower and uses more ink than a general purpose printer like the S750 or a combo printer like the i850.
Oh, and apparently there's an even newer combo printer, the i950, that has been released/launched in Japan. Wish I could find some English pages about that one. And, of course, get a North America release date.