From FAQ on velomax web site:

Q. Why doesn't Velomax use bladed spokes?

"We carefully considered using bladed spokes, but decided against it. In wind tunnel tests, bladed (and ovalized - hereafter "profiled") spokes have proven to be very effective. The caveat here is that they show their greatest advantages vis-a-vis round spokes when the airflow is from straight ahead. As soon as you introduce even a small component of side wind (yaw angle as low as 2 degrees), the larger surface area of profiled spokes acts either as a lifting surface, or develops airflow separation (with related generation of vortices), or both. The bottom line - creation of lift cannot be accomplished without corresponding increases in drag.

Simply stated, a profiled spoke in a static or head-on air stream can be very effective. However, a profiled spoke in a side wind is a propeller.

A round spoke always presents the same small profile to the air stream, whether the angle of attack is head on or from the side. When you consider the wind direction, speed of the bicycle, and rotational speed of the wheel, it becomes apparent that there is an alphabet soup of aerodynamic considerations happening throughout the course of the ride. For this reason, we believe that swaged (butted) spokes present the best real-world aerodynamic profile."