I had a 3' peice of 1" by 3" kick back and it broke a bone in my arm. It doesn't have to be the blade! A guided missle can mess you up just as badly.
That's the one reason I'm not 100% sold on the Saw Stop
saws. Sure, they stop if your finger hits the blade, and that IS a good thing, but they don't do squat for the kick back issues, and I'm afraid they may lead to a false sense of security. My fear of my Delta is a damn good incentive for being careful around the dang thing.
Which is not to say I wouldn't buy a Saw Stop cabinet saw, if I had the money, by the way!