All my plug rods are glass. I think they have better feel, and they also telegraph the plugs action so much more then graphite does. I know I have one plug rod in graphite, and it's the one nobody wants, because for some reason it never hooks up (unless you're actually cast and retrieving the plugs).

So, I don't know if it's the vibrations, but I know it easily shows you the total action of the plug, whether it's fouled or running true, and really shows it when they're slammed.