This used to be on of my favorite races back in my former life as a runner. It was 20 years ago as a high school senior that I did my first B2B. I ran it about a dozen times after that, sometimes serious (once I was the first San Francisco finisher and won a trip to Japan to represent SF in the Osaka Half Marathon), sometimes for fun (once as a "ski" team running as Ted Kaczynski with friends dressed as Monica Lewinsky, Tara Lipinski and Igor Stravinsky).
The most painful times were running with the Reebok or Microsoft centipedes since I was usually one of the 2 slowest guys. Running in a centipede is like being in a 13 man TTT except that you're physically connected by a large nylon sheet around the neck to the other guys and once you start really hurting you literally get pulled along at a pace that your legs just can't maintain. I was usually stuck behind a guy who was a former US 1500M champion and when he'd start sprinting the last 400M with his sub 4 mile speed I seriously thought I was going to die. The only thing that could ease the pain was the endless supply of Gordon Biersch at the finish.
Ahhh good times.
I'm sure I'll try it again sometime, but never as the slow man in the centipede.