I've been using Seafile since April and I am very, very pleased with it. It is one of the few self hosted options that supports client side encryption and manages to scale up to a reasonably large number of files. It fell down on me in the 100k file range, but I was able to get around that issue by breaking my data up into smaller libraries.
The client side encryption was slightly problematic in the 1.x releases. Back then, you had to type your encryption passphrase into the server to create a new library. As of 2.0 you can create new libraries in the client without your passphrase leaving your local machine. You still can't dig through your file revision history without giving the server your passphrase; hopefully that functionality will be integrated into the client in the future.
I took a quick look at SparkleShare, ownCloud, and BitTorrent Sync, but none of them were a good fit for me. BitTorrent Sync only encrypts your data while it is in flight, ownCloud only supports server side encryption, and you can't properly store Git repos under SparkleShare.