ArcaneMagus: LDAP is relevant to Phoenix's link about zmmailboxmove.
Re: why we're not just copying the whole /opt/zimbra/backup - the whole point of this thread (even the the title!) was asking HOW to simply "just copy the latest full backup and any incremental backups after that and then try to restore from that."
If you know how, I personally would absolutely LOVE to hear how. It is the whole reason I opened this thread