AEM begs to differ. This is a graph they used to have on their website. Note that the dry flow outperforms only when there is a ton of dirt on it. A clean to moderately K&N flows better.
Actually, according to AEM, K&N also outflows all the AFE filters too...
100 grams of dirt is a lot of dirt (about 1 cup!). The moral is, clean your K&N more frequently.
If this graph is no longer there, it's probably because others noticed this fine point too... can't sell filters when you clearly demonstrate it aint all that it's claimed to be.
The major advantage of the dry material, at least at this point in the tech, is no oiling. The advantage in filtration is marginal and the perfromance benefits mainly emerge when it is caked with dirt (>120 grams).
They aren't bad, but they definitely aren't better when reasonably clean.