samba - Jul 2006 - Samba Domain Best practice - Backing up Local Profiles

I've recently set up a domain controller and have noticed some issues
with laptop users. Initially I decided to use roaming profiles to
allow for easy backup but have found that if a user works out of the
office, their profile is sometimes overwritten when they login back in
the office. To solve this issue and avoid any data loss I have changed
the laptop users over to local profiles but am trying to decide on the
best way to backup their profiles.

I have come across this same issue a few times on the lists, groups
etc. but have not found a good example of how someone has dealt with
this. Has anyone else out there created or found a good reliable
solution for regular backups of user's profiles?

I have though of trying to use rsync to perform incremental backups at
login and logoff but while logon is easy via logon scripts, I haven't
been able to find any way to perform a logoff script.

Any help or pointers would be greatly appreciated on this.

Scott