The screens on the clamshells are very, very good. The issue with the angle of view in landscape mode is pretty subtle, and it affects reading much less than viewing pictures or movies. That being said, the best way to read your ebooks is in portrait mode anyway - it's easier to hold in one hand, and a finger or thumb lands naturally on the scroll wheel anyway.
I'd recommend a new 1000 over a used Cx60 unless size is a *very* important factor to you. (But then you wouldn't be looking at the Nokia...)
The newer clamshells are more versatile in that:
They have better keyboards.
They have USB host.
They have much better video performance. (The Wireless MMX instructions make all the difference.)
They also have slightly larger batteries (and, by defaut, better battery life as you're getting a new battery over one that's halfway through its life cycle). The down side is that they're a little larger than the Cx60s - The 860 feels pretty small whenever I pick it up after using the newer ones for a while. The difference is pretty small, though.
With prices these days, it's almost worth it to spring for the 3100 over the 1000. I just got my 3100 for $513CAN, while 6 months ago I paid $470CAN for my 1000. (And ~$700CAN for my 3000
) Also, a 3100 comes with a universal power adaptor instead of a 100v one (Not that any of the half dozen 100v adaptors I've got has every caused a problem for me.)
My 2 cents