Yeah, we already switch to Gitlab for code review. But the task management utility in Phabricator are far superior to Gitlab, so it's a bit complicated to switch to Gitlab for now.

There has been three big reasons why we are trying to switch from phab to Gitlab:

* Upstream wasn't very interested in external contributions or hearing our suggestions

* arcanist was a real pita to use for new contributors. Switching to gitlab really increased the number of occasional contributors.

* Setting up CI with Phabricator to run on Diff (the Phabricator equivalent to merge request) was not easy.