I only saw Martin live once, with Tull, in a small venue, scaled down from the big stage, he's a great player, and something amazing hit me, while watching him, his left, and right foot were tapping to 2 separate, unrelated rhythms, and he was playing to both, he's naturally poly-rhythmic, almost like 2 minds rolled into 1 guitar player.
One of the best. His period of King Crimson was my favorite. Saw him play live quite a few times over the years. He was a big influence on my own bass playing.John was an amazing bass player, great voice, and very complex bass lines, made to look simple, when he played them live.