Isn't GitLab a self-hosted alternative to GitHub?
I think the question you were hoping to have answered is, "Why would you pick this over GitLab?". And potentially the discussion you wanted to invoke was, "Is there an advantage to going with a full free software solution as opposed to a product that is primarily proprietary, but has an open core?"
Personally, I think there is, but in the case of GitLab it may not matter. Now that there are some free software heavy hitters (Gnome and Debian) who rely on the open core of GitLab, there is some more assurance that this open core will not become a kind of cripple-ware try-before-you-buy situation. Those groups have enough horse power to maintain the open part of GitLab if they choose to do so.
Having said that, I think there is room for other free software entries in this space and I'm looking forward to seeing how it plays out. In some ways the acquisition of GitHub may be the catalyst necessary to get things started, and I think it's a good thing.
While moving is very painful, the fact that git is distributed means that setting up camp somewhere else is pretty smooth. Even the headaches of the other stuff, such as issues et al, will probably be handled by whoever the new host is.
https://hub.docker.com/r/gitlab/gitlab-ce/ (run as docker image)