I'm not Peter Roberts, but I have received pre-approval on a TN-1 before.

My company's lawyers went through all the "yes this person does deserve a visa" stuff for me ahead of time. When I got to the border crossing (also at YYZ Pearson) I had paperwork that made it a much faster process. I'm comparing this to the previous TN-1 I had which required a lot of questioning, waiting around, etc. If you've got the extra time, I really recommend trying the pre-approval route.

The guys at Pearson are absolutely humourless[0], but they're just doing their job. Neither time did they play any games or use trick questions to try to deny me. (I've heard the ones at the Vancouver land crossing sometimes does).

[0] I make jokes when I'm nervous. They did not appreciate that.