any project or developer that uses it is going to need that backup repository at github anyway
You should have backups of all your projects to media that you control in any case. Google has a track record of winding down stuff it doesn't want to continue (Reader, anyone?), but if you're betting on any source-code repo to (1) not go tits-up (as Google Code might) and (2) not jump the shark (as SourceForge has), you're putting your code at risk. Git, in particular, makes it dead simple to clone a repo and all its history in a relatively compact form, so spare a few GB on a server you control for a mirror of everything you put on GitHub (or whatever).