We've been using GitLab for our production projects for almost a year now.
The biggest reason for moving from GitHub to GitLab was not having to worry about additional cost for creating new projects (we have hundreds of projects and most of them are rarely accessed long after they were created).
It's also neat that we have the ability to customize GitLab if we wanted to, e.g. in 2012 we ran some experiments to create projects from templates directly in the GitLab interface [1]
And lastly, since we're not in an environment with six-digit numbers of users and constant DDOS attacks - we're able to keep a much better uptime than we had before with GitHub.
The biggest reason for moving from GitHub to GitLab was not having to worry about additional cost for creating new projects (we have hundreds of projects and most of them are rarely accessed long after they were created).
It's also neat that we have the ability to customize GitLab if we wanted to, e.g. in 2012 we ran some experiments to create projects from templates directly in the GitLab interface [1]
And lastly, since we're not in an environment with six-digit numbers of users and constant DDOS attacks - we're able to keep a much better uptime than we had before with GitHub.
[1] http://enga.ge/development/creating-a-sturdy-deployment-work...