I am by no means some great dive god, but I have seen and heard of situations exactly as PB described. I had a good friend die last year; he drowned with 1900psi left in a set of double lp 95's. Why? Because he paniced due to his lack of experience in the environment that he was diving. I never did care much for the way air sharing is taught in ow classes, you know, where the OOA diver politely asks for your regulator. I prefer the manner it was taught in my cave classes, where the OOA diver comes out of nowhere and snatches the reg out of your mouth, similar to what will happen in a true OOA emergency. Panic is a great equalizer.