WRT the actual topic, squashfs is supposed to handle files up to 4 GB
without problems. I have not heard of any 2 GB file problems with it,
but my interest in squashfs has been purely academic. I've never run it
in a business environment.
While it is a read-only filesystem, since you are primarily wanting to
keep ARCHIVE data on there, the fact that it is read-only might not be
that big of a problem. When you want to add more archive data you just
use mksquashfs to append it and you're all set to go. This could be
automated through a script called by your tape backup program for
example. Hope that helps.