I have an N800, and I use Alpine on it all the time.  However, note that I
I did not upgrade it to IT OS 2008 and (since I have the Japanese
environment installed) my onscreen keyboard is uim instead of the standard
Nokia one.  xterm on IT OS 2008 has fewer screen lines and the standard
Nokia onscreen keyboard is suboptimal for Alpine use.

Because it has a physical keyboard, the N810 is probably better than the
N800 for Alpine for most users unless you use an external Bluetooth
keyboard.

IMHO, the difference is that Alpine is primarily oriented at handling huge
volumes of mail as efficiently as possible; whereas most other programs
are focused at presenting a particular user experience, without regard for
whether it is efficient or can handle large volumes.

I like making jaws drop by showing Alpine on the N800 open (and thread!) a
55,000 message mailbox in a matter of seconds, all the while emphasizing
that nothing is kept stored on the N800.  I first did this after some
clown claimed that IMAP can not work well on mobile devices with more than
a couple of hundred messages.

If you want to open godzilla mailboxes and thread them on a regular basis
on your N800, you ought to get the binaries from
        http://staff.washington.edu/mrc/N800/alpine-new.tar.gz
which are based on our current development sources.  We fixed a
performance bug in threading that showed up on slower platforms such as
N800.

-- Mark --