Hi RequestedDeletion,
Something I was thinking about this morning on my way to work, this system you have replicates users and groups as well as data to create the redundancy.
Is it possible to have a stripped down version that only replicates users and groups and passwords (not data or ibays) so users would only have to authenticate once and good old admin (that's me!) would not have to setup users on more than one box?
There is probably a better way to do this but my attempts at rsyncing with samba groups etc. came to naught.
Cheers!