* If you'd like to migrate from a self-hosted GitLab instance to GitLab.com, you can copy your repos by changing the remote and pushing to the new server; but issues and merge requests can't be imported.
* When you migrate repositories to GitLab, there is no restriction on maximum size. They are imported via HTTP, but if the repository is too large, it can timeout.
* Repositories are imported to GitLab via HTTP.
If the repository is too large, it can timeout. We have a soft limit of 10GB.