I also ran a PunBB forum (an automotive forum) for about 6 years before selling the site to VerticalScope. It was the largest PunBB-powered site for quite some

I also ran a PunBB forum (an automotive forum) for about 6 years before selling the site to VerticalScope. It was the largest PunBB-powered site for quite some time, by number of posts and users, and considering that it's still running the same old version of PunBB to this day, I'm guessing that the VerticalScope team couldn't figure out how to migrate it to InvisionPowerBoard. Shocked they haven't been hacked and defaced, but PunBB never seemed to attract much attention compared to PhpBB and others.