How could a cap that can only pass 2.4mv of AC and zero DC have saved you from a heavy shock? The death cap provides absolutely no safety but does add the substantial risk of a shorted cap with wall voltage AC on the chassis. The light shocks you received from amps with death caps were actually caused by the death cap because it passes AC onto the chassis if the cap is connected to the hot wire instead of the neutral. The death cap didn't save you from heavy shock, it just gave you a light shock. If the amps that gave you a light shock didn't have a death cap you wouldn't have gotten any shock at all.