I use a comic pdf to test turn page speed.
sony prs-505 vs cooler
http://www.youtube.com/watch?v=zKymsM0tp_Y
sony prs-300 vs cooler
http://www.youtube.com/watch?v=4zHSyepjULE
PRS-300 is very very slow on turning page.
Cooler is more fast than those two devices.