A month ago I created two mirrors for the KDE Connect repositories in Github, and I’m really happy with it. Projects in Github are more discoverable than in our internal KDE repo (our GIT web interface is not even indexed by search engines!), and makes it easier for new developers to get involved and send contributions, like these pull requests. Of course, I have no plan to drop KDE’s Git repo: Github is not free software and we want to make sure our code is always accessible through our floss-based infrastructure. Also, the KDE repo is nicely integrated with our tools, like the bug tracker and review board, but I still think that having a mirror in Github is a good addition.
Other free software projects already host mirrors in Github (see Gnome), and they even have support just for that use case: Github Mirrors. I think we could greatly benefit from doing something like that KDE-wise, as we would both gain visibility and reduce some load from our servers. As of now, I’ve done it with KDE Connect and I have no regrets :)
Edit: Made clear that we will always allow access to our sources via our free infrastructure.