Sometimes work, sometimes don't. The problem is with the discussion counter not being always reliable. Unfortunately the author was unable to replicate the bug but at least he tried. I have however been able to replicate the bug on stock 1.3.3 and 1.4.0 RC1 installations.
Installed due to being exactly what I was looking for. It does not work on xF 1.3, although add-on states it is compatible. After installing, posted asking about it, saw last message on Mar 29th (one week) asking for help, no reply... Hopefully add-on is still being supported and will be update. Will rate again once corrected.