IMO, the security line doesn't move so quick because of so many lines open, the reason it moves so quick is because any bottleneck is usually at customs, and the flow of people coming through there manages the traffic for security. Get Nexus, you get to skip it there, too. Since there is no pre-clearance in the US, TSA can't do anything to match this.

In regards to the original topic, yes, elite line is for AC elites only and the right Amex cardholders. I've had some luck when in F on UA, but usually not. Since transborder security lines are rarely an issue, really there isn't too much of a difference.

And to the OP, I agree, most of UA's YYZ staff are great!