I'm running rsync to keep two filesystems synced up between two offices and it's working very well for me.
Here is an example of the command I'm using.
The first part, /opt/Files/ is what I'm copying, the second /Volumes/nonboot/opt/Files is where I'm copying it to. --delete is removing anything in the second directory that doesn't exist in the first directory. (Keep in mind, this command is running on the machine that relates to the second directory)
I'm running this via Cron and I have sshkeys setup so it doesn't require me to enter a password. Hope it helps some.
rsync -v -r -a -e ssh $ipaddress:/opt/Files/ /Volumes/nonboot/opt/Files --delete --progress