We moved from Phabricator to JIRA, Github and CircleCI. We couldn't be happier. It's one thing to have a single tool with 70% of the functionality you need, it's another to have 90%+. That 20% makes such a huge gulf it's not even funny. We were able to ditch several thousands of lines of cobbled together glue that moved us 10% forward but added overhead for any new project which set us back a week or more.
I self host it at home. Haven't had problems but probably only because of how small my instance is (10 people). The omnibus installer makes it relatively simple to maintain!
Exactly my feelings about Phabricator. GitLab simply runs circles around it if you consider the issue tracking, CI etc. as part of the problem.