Installed today using the Production Mode guide, so far no problems and all my team in.
Some experienced some minor issues and also had some problem restoring GitLab login (here I think that I configured it but had to restart Mattermost to make it available, as the link was there but return errors). Also a problem with the email, the link in one was not working and after some restart it allow people to join, after fixing also GitLab login. I hope I can make some test even if now it's getting used more constantly.
Anyway, thanks for your great work! The progress so far has been amazing, still pushing to make it the communication tool here.