We didn't move away (never were using GitHub), but we've done our CI hooks from inside arc (the command line client for phabricator) and it's worked pretty well (it means you need to be able to reach both phabricator and our CI server, but since phabricator is self-hosted that's not really a problem). A little manual, but pretty straightforward to get setup.

Overall, we greatly prefer phabricator's review tools (batch email notifications) + general git workflow (linear history on master) so haven't really looked into GitHub enterprise.