Never got notified that you responded- just happened to see it... odd.
Anyway, the biggest drawback is that 5 private. However, then you don't actually have to deal with servers. Which I think GitLab has a pretty heavy draw from a single commit/pull on a small single server. Which properly scaling will likely cost more than $7/m.
As for everyone else forking a repo, public is an option on GitHub. If they wanted private- that doesn't really have to be an issue you specifically need to handle.
I'm fine with either nonetheless- if you can support GitLab and don't want GitHub.. go for it =p.