Hmm, I know bol.com will start selling a sony, not sure which one though (I've seen pictures of the 700 and of the 505 with news articles)... They said after the summer. And as the summer is about to start, it should be in about 3 months
(
http://www.bright.nl/e-books-downloaden-bij-bolcom)
About reading on a 6" screen: there should be BeBooks on display at all Libris and Blz shops. (try this site to find one closest to you:
http://www.libris.nl/?winkeloverzicht).
Or you could make a "mockup" of a 6" screen. I don't know what the measurements exactly are (at least of the screen itself), you'd have to ask that of somebody that does own one