Originally Posted by AGSF

Agreed. It's especially bad in Toronto.

Execution is key. It would definitely add on additional time at the beginning (or middle, if transferring) of the journey where I'd personally prefer screening to be expedited. Often, it takes no more than 10-15 minutes to clear immigration (at least for US citizens) in the US, but they'd have to build in at least an hour or so like they do in Canada for pre-clearance, which would really not be a good thing.

Also, as a Global Entry member, I see very little appeal in the LCY-JFK flights, even if you work/live close to LCY. If all you have is a carry-on, it takes no more than 5 minutes to get from the plane to a taxi.