Well Crazycanuck - that's a difficult one!
but is it actually increasing or decreasing overall safety?
IF there is an attempt to take the flight-deck it will almost certainly foil it, and therefore safety is INCREASED. IF, however, we go through for ever without, then it will have been a definite DECREASE.
It is still possible, though, with serious effort from both sides of the locked door, to 'manage' in the CRM style. It just takes that ongoing effort, and none of the 'them-and-us' attitude.
We'll have to excuse old 411A, I'm afraid, who has not caught up with phases 3 and 4 of CRM
PS Thanks for the link, alf5071h