I have had two 5" 4:3 aspect ration ereaders; the Sony PRS350 and the Pocketbook 360. They just don't look right. The 3" width is OK but 4" just isn't high enough.
I think the ideal ereader (light and portable) would be 5.5" 3:2 aspect ratio. This would give you a screen size of approximately 4.5x3". An amoled 900x600 (200dpi) @ 8oz would make me happy.
I have a Galaxy Player 5.0 due here tomorrow (5" 5:3 aspect ratio). I'm hoping this will do the trick but 15:9 is real close to 16:9 and is not my favorite aspect ratio.
I think we should let Samsung make it.
Regards - John