These ideas all have merits, but must be weighed up against the problems they cause. How about a beefed up door which is normally locked before take-off until above a certain FL, but open during cruise for CRM/Food purposes. The door needs to be capable of being broken down within a minute using sufficient force in case of the sleeper scenario. This needs to be tied in with an effective CCTV system so we know when to hit the lock button if trouble occurs. After these precautions I think we all realise that its up to the pax to look after themselves, be it in the case where the door stays locked after trouble flares, or in the case of forced/sleeper entry to the cockpit that they can overpower the hijackers then. Most of us only have jobs because air travel is relatively cheap at the moment, lets bear that in mind.