[Havoc]

Open source...interesting...so one could jam an encryption layer in between. Make use of the free storage w/o privacy & security issues.

[kijin]

The synchronization software doesn't need to be open-source in order for you to throw, for example, EncFS into the mix. Open-source might make integration easier, though.

In either case, you will lose one of the most powerful features of Google Drive, which is that you can search and edit your documents online.