I have both - a jetbook (newegg on their $200 sale when it listed for $300) and a prs-505 (Border's $200 sale). Personally (and I am in the minority I am afraid), I like the jetbook for reading. The Sony due to the fact that it handles SDHC and the jetbook does not means that the Sony stores lots more books. I had one of the origional Sonys and hated it due to the supplied software. The newer sony does not require the library software that stinks. No clue on durability yet - the origional Sony I had died one day after the warranty ran out and the repair cost was close to the cost of a new one so I just tossed it.
Jetbook support is mostly DIY, but there is a decent community.
I never ran a pages viewed trial on them - since I always carry a couple of USB battery chargers.
However, presently I am taking the jetbook with me for daily use, the Sony for at home in good light, and (in another thread) for nightime reading, an ONDA 545HD for txt files (NOT a dedicated ebook reader - a multimedia unit).