Steve Cramer wrote:

http://www.atpaddle.com/WhitewaterGateway.html

The AT3 and AT4 paddle blades look very poorly designed to me.
In any asymmetric paddle, the surface area on one side of the axis
should be equal to the surface area on the other side of the axis,
to help prevent flutter when the paddle shaft is loosely held.
Preventint flutter also helps avoid too-tight gripping.

I can't quite discern axis in the AT2 picture, but the AT3 Edge
and to a lesser extent the AT4 Play seem to have more surface area
on the upper half. The ATX and Zen blades look more equalized.