I was a big fan of Perforce up to a point.
One day we found it had mixed up a code unit, leaving the wrong version in a build although the tooling told us it was up to date.
After a long battle and a good kicking from maangement we finally found the problem and had to manually patch the file into place as the tools refused to acknolwedge that the wrong version was there.
I could have forgiven this, but I contacted their support and sales (as they were a 'free small team' user but may have adopted the tools company wide). After an initial warm reception from sales, we got support who essentially 'gave up' after 1 email back and forth. Perhaps the direct evidence contained that their tools were unreliable caused some sort of internal conflict? Whatever, the support guy 'went on holiday' and the case went cold. Even after pressing the sales director, we were roundly stonewalled.
One of the main reasons comapnies use proprietary software vendors is to ensure when things go wrong that there is someone to ring and get help from. Unfortunately in my experience, when things go wrong, Perforce just go quiet.