yeah there was something in there about UV rays can make the original valve brittle and the hose connected to it could get caught on something therefore cracking the valve causing it to leak. i'll admit the original valve was kindof brittle and the new one feels like much better plastic or whatever they use.
as far as hitting something that's not gonna happen. i have hit things with the gas cap and the rops (even folded down) like low hanging tree limbs. the valve is tucked in behind the gas cap so i don't think you could ever hit it on anything but who knows what will happen if you flip over.