Here is an interesting article with test data from Zipp.
Zipp PDF
From the reading I've done, rim shape is more influential than spoke shape, and the combination of rim shape and spoke profile are important to the final result of "aero" advantage. In short, bladed spokes on thier own may have little to no effective advantage. But when paired with a compatible rim profile under some wind and speed conditions DO have advantages. Is that advantage noticable to the "average" recreational roadie? That is a bigger question. It seems that the difference is a few seconds over 20 kms at average to higher speeds. And, under less than favorable conditions, you may actually have more drag with certain wheels/spoke set-ups.
Bottom line is, if you like them go for it. But, don't expect it to put you at the front of the A ride next Saturday. I personally would love to have a set of Ksyriums cause they're strong, light and super cool looking.
