Palm T3 is my present "reader" (I use eReader because I can mark up my own RTF texts with a Word macro). I do find the screen bothers my eyes after awhile, the white text on black
does seem to be easier on them, though. I probably get closer to ~4 hours.
I
do like the fact that I pretty much
always have it with me so I can pull it out and read when I find myself with a few minutes on my hands. The small screen size isn't nearly so much of an issue for me as glare (reflections) and washout are. I have noted that the brightest setting on a T|X is a good bit less bright than the brightest setting on the T3, so those last two issues would likely be worse in it in a lot of situations.
Personally, I'd far rather have a dedicated e-ink reader.