I have computers in multiple geographically-diverse locations and need a large amount data (terabytes) to always appear in each location. Other requirements:

1. Direct sync between my devices, with no third-party cloud involved

2. Fast local sync when two devices are on the same subnet are detected

3. Since individual files can be 20 GB in size, interrupted synchronizations should automatically resume when the connection is re-established (without having to start over from the beginning)

4. Encrypted transmission of data, but not encrypted on disk

5. When renaming or moving a file from one folder to another, the system should be smart enough to detect that there's no need to re-transmit that file (i.e., it just needs to rename it or move it to the new location on all other devices)

6. Ability to throttle upstream/downstream bandwidth on a per-device basis

Neither Dropbox nor CrashPlan -- nor any other tool -- has been able to meet all of these requirements.

In short, this is a very exciting and welcome development. I sincerely hope that this problem will soon be solved!