At Yugabyte, we currently use Phabricator, and we are trying to decide between switching to GitHub PRs vs. upgrading to Phorge. What potential issues exist in upgrading a Phabricator installation to the current version of Phorge? How stable is Phorge?
Phorge is stable, and works as a drop-in replacement for Phabricator. Most of our work right now is rebranding (as we are not allowed to use the "Phabricator" name).
Very shortly, we will be publishing an upgrade guide (see T15026). In short, to upgrade you have to point your Git remote to the new repository (rP) and do a standard upgrade as documented in Diviner.
We think it's ready now: https://we.phorge.it/phame/post/view/1/going_public/