I have a set of the Anthrax ones, they have the kevlar-esque knees though. So the knees can take a beat, but they're soft and comfortable slick jogger material. They're a brilliant compromise. Really happy with them. Had them at CPPS last weekend, easy clean, and zero damage from sliding around.
After looking at the Amsterdam weather report, I packed them and my BK Supreme pants. Have a feeling the more water proof ones will be better served this event.