Perkin - I'm not convinced about gate security. VIE operates a mixture of gate and central security, dependent on which terminal you're in. Gate security there works well on the smaller aircraft but when it's a large one it's a very long queue, epsecially as they often combine the security check with a passport control check. Often the central check at VIE is quicker. The one big advantage of gate security is you can elect just to sit in the coffee bar opposite and wait until the queue subsides, as it will once the majority of pax have passed through. Obviously you can't do that with the central security.
Interestingly, that particular airport, VIE, introduced gate security in that terminal because the previous central security area was inadequate and there wasn't the scope to increase it's size without encroaching on the retail units.
One other disadvantage of gate security in a large airport is that it's sigificantly more expensive than central. Though at VIE they decided those extra costs would be less than the loss of income from retail units.