My only comment to the above post is that there is often a lot more that determines the potential speed of a kayak than just the raw water line length to width ratio. I have paddled boats that by their length and width, one might conclude they should be fairly fast, but for various reasons they seem to prematurely hit a wall.

I'm not a racer, but it seems to me that it would be very important to have a boat that is fast but also handles well in all types of water and wind conditions. That might take a good deal of time in the cockpit.