Actually, you can do a swipe gesture with the 600 and 900 to turn pages. The default is backwards from the iPhone, that is, you swipe from left to right. Quite honestly I think Sony was stupid for making it backwards, but you can reverse the swipe direction in the Settings menus.
I had a 900 for about 10 days before I returned it. It was impressive except for the screen, but at $400 way too expensive. I decided to go another route and got an Asus T91MT netbook tablet. For less than another $100 I got a touch screen device with a real OS, Windows 7 Home Premium, that is completely open and runs every eBook reader I will ever need. Plus it does an excellent job of reading PDFs. It isn't for everyone, but it is the best solution for my needs. I still have the 300 for portable reading, but even it needs an addon light in darker environments. I considered waiting for the iMaxiPad to be released, but I prefer open devices with real OSes to toys made by Apple.