I would think that a j-stroke is very efficient, but like stated at a
moderate pace. I'm thinking that a kayak paddle may be a little better
in some situations because you should be able to get a higher stroke
rate. My friend found the kayak paddle was more efficient on steadies
than his whitewater paddle, and he's a fairly competent canoeist. I
don't know how large of a difference there is between a WW and a
touring canoe paddle.

Andrew