I must say the best system, and full comps to them for doing it,is with Comair in South Africa.Unfortunately it only apply to local and regional flights.
There you take your carry on trolley to the bottom of the aircraft steps. There it gets taken from you and put into a separate hold (clearly within your view) and you get it back at the bottom of the steps when you disimbark. This takes care of the security aspect for me and I only carry on what I actually need for the flight.
But I can see that this would be a problem with the larger interantional flights/jets.
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