I think anyone is ineffective if the attacker has a firearm out and pointing at you,be silly to try to bring yours out unless you thought they would shoot anyway,then most likly both shot you twice since he had his out him once,with you having the biggest problem.
Last resort situation,distracted stand a chance,against other weapons stand a bigger chance,like ball bat at ten ft and you see it coming.
Carrying a gun does not mean you wont die,but stand a better chance of taking them with you or averting it all together.
Would it pay to stop a crime if it resulted in a gunfight,with others in the vicinity.
Assuming they are whacco yes, otherwise no.