I'm sure just about everyone on this board that has a 350 reads for hours at a time.
Remember, the screen resolution of the 350 and 650 are the same (600x800), so you actually get a higher DPI with the 350. The 650 displays more text per page.
As far as font size, I
THINK that Sony scaled the fonts so that the text size of the 350 and 650 is the same. Can anyone who has both verify this?