I've though about this a bunch even though I'm not a kayaker.  I think one of the contributing factors to Scott Bristow's death was the hand paddle/kayak paddle issue.  Scott always hand paddled - but because he was paddling big stuff (Great Falls on the Potomac) he brought out the kayak paddle.  Rolling with the kayak paddle wasn't his problem - he rolled several times after he got in Charlie's Hole - but I think that he was less comfortable or not at the top of his game with the kayak paddle because of all the hand paddling.

Julie