Hi MxxCon,
You are absolutely right, version control through a ftp client is everything but professional and funny enough my company is currently implementing an SVN service based on Redmine I believe. We have grown quite rapidly the last couple of months so we indeed needed a better way of handling version control with the explosion of colleagues that we had. Really looking forward to working/playing with it as well as my bugfixing ways will become a lot easier I hope.
However, for my own little custom developments @home and perhaps some small startups or other 'do it yourselvers' this custom auto rename feature could be really handy, if time/money doesn't permit a running SVN servive. Plus it makes flashfxp all the more better