I just started hunting crags mainly for their silks, but I have not had much luck with the drops. So far, the maximum number of silks I have obtained from crags is 2. Carrion spiders, on the other hand, have had up to 5 silks at a time, with the average being 2 to 3 silks.
Am I just having bad luck with the random silk generator or what?
As for my experience fighting the crags, they hit hard, sometimes up to 42 points. The poison is pretty harsh, but thanks to having two druids in my group doing nothing but heal, heal, heal, I've never dropped below half my HP's. Melee always have a good healer or two handy if you want to take on the crags. I would suggest not starting on them until one reaches 16.