Anecdotal, and I could just be unlucky, but I have found the USA preclearance agents in YUL to be amongst the most unfriendly and pedantic pretty much anywhere on the planet. Even with NEXUS, I have _twice_ been stopped in the last ~5 years, and had to produce receipts for, in one case a couple of friggin' sweaters (it was January), and in another just for random secondary inspection. It's the only CA airport where I've had anybody do anything other than just wave me through.

The NEXUS / Global Entry line is obviously WAY shorter than the normal scrum, but if you don't have your physical card, I'd just assume an additional 15 minutes longer than you'd normally account for departing from a Canadian airport. *shrug*