Not often enough. Been to two Protomen concerts and Weird Al's first "laid back/retirement" concert. Always buy at least one piece of merch.
So less than one a year. Was going to go to the Flaming Lip's Yoshimi anniversary concert, but life got in the way and I couldn't snag tickets.
It's something my wife and I talk a lot about, but life keeps getting in the way of us getting out to them.
We get out to local opera and classical music stuff a little more often, as my wife is somewhat involved in that scene, but I assume most people don'r think of recitals as concerts.
Unfortunate to see that they haven't tested with xash3d or the like. I'd be especially interested in the ray tracing fork of xash being supported.
Improved lighting does wonders for old games, imo.