I have recently been having the same argument as to if I need to replace my lid. Mine was on my head and I fell of at Snetterton during a track day. I did not hit the helmet on the Tarmac as I fell of in the gravel. The helmet did not take much of an impact but I did manage a few army style rolls through the gravel and the helmet has quit a few stone chips in the paint work. Still not sure what to do or if it needs replaced.