As I work daily on my office computer and home laptop in a Windows 8 environment, I have been using an external disk as a backup/sync unit: semi automatically, once the disk is connected, a bidirectional sync is done. This helps making data portable and gives an extra backup:
Office data <-> External disk data <-> Laptop data
Downside: you need to perform synchronization each time you have updated data on the computers. Once you forget to backup/sync, you're out of sync.
Solution: use the external disk as main storage, while internal disks are backup units. In this scenario, the external disk holds the most updated data; only in case the external disk is unavailable (forgotten somewhere), you'd be working "offline". Subsequent sync would update data on the external disk.
As for the synchronizing process, you would configure the PCs to sync on the fly, as soon as an update occurs on the external disk, or on demand.
Your thoughts? Any better idea?