I've now had these pads for quite some time. They are stained with sweat, dirt, mud and paintballs and have numerous scratches all over them but my knees and elbows are fine. These are still the best knee pads I have ever used and they are still going strong despite the constant abuse they take.
I take these out atleast twice a month to play or ref and generally have to wear for for 10-12 hours at a time and there is no problem. After they break in they don't pinch alot and they're light enough to forget you're wearing them after a while. Quick to put on when you're in a hurry quick to take off at the end of day when you're tired and covered in filth.
Should my set ever break I will definately be buying another set.