Used a Palm T3 (and before that an M515 and before that a PalmPilot Professional) for years. Now that I have a Sony, I wouldn't go back to them for reading. The screen size is a big part of it, but the clarity of e-ink vs. LCD is more.
I'd suggest you try out one of the PDA readers (find a friend or a store that will let you) and see if you think it will do for you.
Whatever you do, don't look at an e-ink device unless you're pretty sure you don't want to go the PDA route -- e-ink may spoil you instantly.