Maybe I'm just a train nerd.
To me, 5 hrs spent on a train reading, working, and sleeping somehow feels a lot more enjoyable than 5 hrs spent jumping between checkin lines to airport security lines to airport lounge lines to pre-boarding lines (shuffling between AC's zone 1, 2, 3, 4....) to lining up to get seated to waiting for take off to preparing for landing to waiting to for a gate bridge to lining up to deplane to picking up your luggage on the carousel to waiting in line for another taxi at YUL. One thing I noticed when flying between YUL-YTZ/YYZ is that my Fitbit step counter shoots through the roof for the day because the number of times I had to get up, walk, wait, sit down, over and over again in a 4-5 hr window. I admit that YTZ-YUL or YYZ-YUL is a faster proposition, but it's a near hellish, seizure provoking experience even for frequent flyers with airline status.