Gerrit is it’s own server and the issues we’ve seen were with the client and have recently been fixed in the brand new version of JGit. It also didn’t corrupt the repository, it just pushed packfiles that were missing objects. The Gerrit server is solid and has been used by the Android project for over a year.
However, since it is its own server and enforces a very specific workflow, it is generally not used in conjunction with public GitHub much, since code contributions on GitHub tend to be pull requests, where contributions on Gerrit are peer-verified patch series through the Gerrit system. Again, you can set them both up for the same project, but most people do not.