My company has a Mac OS X fileserver in our office in DC and an office in San Francisco. Though we have 100/100Mbps fiber in each location, working with large files over the WAN was still slow. We added a Mac OS X fileserver in SF and now sync the folders of clients we share between the two servers, which allows each office to work on the same files locally. Because we replicate Open Directory between these servers, permissions are maintained after the sync. The only drawback of this setup is that we must be careful not to edit the same documents at the same time as the second sync will push the first into the history without merging changes. This has turned out to be much less of a problem than I anticipated at first. We are currently syncing over 1TB reliably between these servers. The only real problem I have had is that I can't get BT Sync to reliably connect without a relay every time. I have tried all the tricks to avoid relay connections, but I seem to always have a few "cloud" icons next to some of my sync folders. Hoping to cure this once and for all with a point-to-point VPN between offices in the near future.