I didn't personally meet Karl Sanders, but my two guitarists did at the Nile show last week. They went up to him and said "We love your Mashall amps....." and then Karl proceeded to talk about amps with them and was completely cool. One of my guitarists asked if Karl was going to be using one of his guitars that my guitarist LOVES for the show, Karl replied with "No" but then offered to get it off of the tour bus and let my guitarist check it out.
Seemed like a really cool guy! I have heard some stories about him being a dick, so that was nice to hear something good. Also, George Kollias messed something up on his drums and Karl started a "DON'T BREAK YOUR DRUMS GEORGE" chant