Just got back from the computer store. I was comparing prints from an Epson 820 and the Canon S820 with a 10x lens.
The Cannon got the marks for the sharpest circles (the Epson seemed to have more aliasing on the diagonals). The Epson got the marks for color representation though. There appeard to be vertical banding on the Canon in the hightones. Skintones had noticable cyan vertical lines through them (at 10x). These were not visible with the naked eye however. They both appeared about the same with midtones. The Cannon looked like truer lowtones.
Looking at the price is probably the closer for me-- Epson 820 = $99, Canon S820 = $299. I can buy a lot of ink and paper for $200!
Unless you all have another suggestion, I'll probably go with the Epson 820.