I got my 902 yesterday, updated the firmware and tested opening times for a bunch of PDF and EPUB files. Most are O'Reilly technical manuals, with one picturesque physics book (Motion Mountain Physics vol.1
http://www.motionmountain.net/), and a couple of texts I scanned myself at 300 dpi. I've attached the results to keep the table formatting sane. I measured the time to open each book for the very first time, browsed about 30 pages into it, closed it, and then measured the time to open it again immediately after.
Page turns generally take about one second in all cases, except for chapter changes in EPUBs under fbreader, which can take quite a few seconds.