Cool.... its neat to see others develop paddling skills and pushing the limits that are not main stream.
But I guess my biggest concern is about self rescue. Lets face it we often try harder things during our paddling development.... just pushing our selves in each new situation. Most times reason and past experiences help us decide where our limits are, that said we ALL take on the task of counting fish.

Running class II/III water standing up certainly is one of those areas that throws the risk factor up but limits your options as far as your self recue. It only takes that one mistake and over you go, and in many cases relying on your friends to catch you and your boat. Yes thats why we paddle in groups..... but we should try to limit the situations that we put our selves into, like the ones where we our selves can not help our selves.
Yes I run class IV plus and low V's, and yes the risk factor is high, but my first consideration is will I be able to self recuce if I miss a stroke and find myself checking out the bottom of the river or stuck in a hole.
That is where a roll is your best friend..... not having to rely on one of your buddies to chase your boat as you swim to shore.
Standing up takes that option away from you.
_________________
Al Greve http://www.canoewateradventuring.ca South Western Ontario's canoeing specialist