In a true gunfight, the adrenaline and "tunnel vision" focuses will cancel out your brain registering the report. Ask anyone whose been in one and they'll tell ya that they don't remember hearing the shots.
I threw in a "no" vote... mostly because I had ear surgery last year and now I have a couple holes drilled in the side of my head- and almost a year later, my hearing isn't any better. Oh- and my Dad never used hearing protection in his younger years and he can't hear the beep his watch makes out of one ear.
I definitely agree with the idea of being prepared, but I don't want to sacrifice my hearing for that. I think I'd be worse off if I couldn't hear in general rather than being more prepared for the Boom in a self defense situation.