If you already have projects on GitHub that you are working on, we prefer that you continue to use GitHub due to its open nature. We’ll gladly push and pull code from your public repository. We provide GitLab locally for projects that are just starting up, have sensitive data, or are not quite mature enough to be pushed out into the world.
Yes, and we encourage you to do it when your project is ready, or you are starting to publish results using your code. In fact, our data policy requires all data and code developed at SESYNC be made public if possible. While we’ll gladly host a public GitLab repository, we expect you’ll have much more exposure if you move your code to a mainstream service like GitHub. Also, for some journals, it is becoming a requirement that you move your code to stable open repositories for long term hosting.