Did you end up getting this sorted out?
You didn't mention if you were in a MS environment, but if you are then DFSR would be the way to go. DFS/FRS was completely rewritten for Windows Server 2003 R2 and became DFSR. DFSR is a huge improvement over DFS and as it only replicates bit changes, it's great for sites on slow links (ISDN??).
We don't replicate Moodle data off site, but we do use it to keep all the web servers in sync with each other.