I was using a Bonzi pipe guard that looks just like RM_guy's. I think that it was better than people think. At the last enduro it took a real beating and protected my pipe from dents and rocks. I agree that the e line works the best but at that same enduro a riding buddy crushed his e line and pipe on a not so hard crash. I just bought a 2 piece guard at a local shop, it was used and I horse traded for it. I thought it was carbon fiber but after examining it, it appears to be fiberglass. It fits nice and should protect fairly well, it will probably bust up in a rocky crash though.
I wouldnt hesitate to get the Bonzi pipe guard, I think that it is a good choice for the money, the eline is the best but much more expesive.