Hi Peter,
Welcome to the AtoM community!
I think it's possible that AtoM's ability to generate finding aids from archival descriptions may meet your needs. AtoM can create a finding aid in either PDF or RTF (if you want a version that can be easily edited in a word document program), and offers two modes of generation - an inventory list (which is useful when you have no or minimal details at the file and item level - in this case AtoM will just provide a summary table for these levels of description), and the full details option, which includes all metadata elements at all levels of description. For more information, see:
It doesn't cover all levels, but AtoM can also generate File and Item list reports, for lower-level records. See:
Also, please note that a finding aid wouldn't really act as a backup, in the sense that there would be no easy way to import the information back into AtoM in the future. For something you can still import, but that is a bit more readable than an XML file, you might consider running CSV exports. See:
Finally, if you're interested in just backing up your AtoM data in a way that could be loaded back into an AtoM instance if your server experiences some kind of catastrophic failure, please see:
When users upgrade, we typically recommend creating a new AtoM instance and then loading your backups into it and upgrading the data schema - so our Upgrading documentation describes how you would load these backups into a new AtoM instance:
Hope this helps!
Cheers,