This debate is all very interesting, pros, cons, quid pro quo, QED.
All bloody marvellous.
But pointless anyway. Quite simply outside the USA pilots will not be armed. End of story.
In the USA with all it's enthusiasm for guns some will, in fact are being armed. But it will be a minority whatever happens. It won't last though. With locked armoured cockpit doors, passengers not willing to die for Allah and the relative difficulty in getting weapons on the aircraft. The 911 scenario will never happen again.
It's time to move the debate on and consider the next real threat, which is of course SAM missiles and bombs in the luggage.
One or other I suspect before the year is out.