Vancouver is more expensive, and Toronto has more traffic, from what I've heard, but the low salaries in MTL sound like a downer.
Income distribution is somewhat more even in Canada, so maybe you don't make as much but the people in 'lower' positions make more, relatively. This is actually a feature, not a bug - the city is safe, there is still a middle class, public services work (relatively) well and you can walk around as a tech person without worrying about a person randomly punching you.
Second is that you will not have to worry about, and save for, large costs like health care and schooling. People in the US seem to go way outside of their budget just in order to get into a district with good public schools, or, pay an obscene amount for private schooling. That kind of adds up over 18 years. Private schools in Canada exist, but by no means are you disadvantaged in life if you grow up in an average middle class area and go to a public school.
One more question- how's the climate? Montreal is north of Chicago and New York, after all...
I heard last winter was much colder on average, though I was lucky anough to spend that time on the west coast. Coming from a few other places in Quebec, Montreal so far strikes me as having milder winter. Probably harsher than NY, though.