The dash 8s and at the gate I would understand too. But why before security? My reluctance has got two reasons. 1. I make sure that mine is the correct size according to the website. But the handle can get puffed and if you push it down into a physical sizer it would fit. But it may not show the size in an electronic sizer because the handle is puffed up. 2. Most of the time, I am coming off an International fight and doing a layover and then taking a morning flight. There is lot of stuff one would need on a 14 hour flight. I have had my stuff stolen in such an incident from my hand luggage as there is no lock on it. Plus I have fragile electronic items in it too.