Every Sparkleshare article needs a "that's nice, but people should really take a look at Unison if you want to sync files between computers" comment (I've done most of them on LWN).
So here it is :-)
Unison is much more flexible, and actually made for that purpose. Using git as backend adds a few problems that Unison doesn't have.
"Share" is the important part of SparkleShare, it's more for "many people using the same files", than for moving your own files onto 10 computers and have it all synced up to your main server at all times. So I guess you could quickly use both.