I'm going to browse through the 20 pages of replies soon, but has anyone already mentioned the rendering accuracy? My Kobo renders pages much less accurately (in terms of graphical embellishments and spacing, sometimes diagrams) than my Sony does. There are good reasons for me to use my Kobo instead, sometimes, so it would be nice if I could guarantee that they look the same. It's a bit disappointing that my PRS500 renders the books I buy from the Kobo store better than the Kobo (1st gen) reader that I have.
Part of the problem is that the desktop reader itself also renders these elements incorrectly, so I guess it's not limited to a firmware request.
Anyway, if it's unclear what I'm talking about, I'll post some pictures later.