Since hosting git repositories is core to your business, you should take the time to do it right (https://www.eclipsecon.org/2013/sites/eclipsecon.org.2013/fi...) instead of using vanilla git and relying on a magic filesystems and vertical scaling to solve your issues.
The presentation you linked is something we've considered. But it is build on top of Google's distributed filesystem. So we consider our move to Ceph a first step in that journey.
