Except running a git server is little more than having a place to store a git repo and giving ssh access to it. There's really no maintenance if you already have the server. What github et al provide isn't repo hosting so much as fancy UI tools on top of that.

Edit: seriously, I wonder how many people who just automatically go to github have ever bothered to try the simple act of creating a git remote on a file server on their own network, or even just to a different host. It's really easy, and it really underscores how simple it is to have your repo distributed without any 3rd party infrastructure. Once you see that, you see that putting a copy on a shell account on your hosted VM is dirt simple and requires almost no administrative burden.