I can jump in here since I'm a Canadian guy with a US permanent visa...
Canadian shcools are harder to get into...mostly because the "in-state" ratios at a lot of schools are in the 90% range. (Yes, 90% of students selected will be "in-state"). That combined with the cutoffs, less schools and the larger number of students applying per spot makes Canada a hellish place for medical school admissions. It boils down to the fact that most people here have only 1-2 schools with a realistic shot of being interviewed at. If you don't get into one of those two schools you're probably out of luck. In the US, with so many more US schools, and more importantly, many more private schools, the guy that doesn't get into his state school still probably has a decent shot a 5-6 other schools. In Canada, there are only about 15 schools total.
A good analogy would be:
Imagine being limited to apply to 15 schools total, where you are required to apply to all California schools counting in those 15, and you're an OOS.
To answer the OPs question, you don't actually have to be that much better. a 3.7-3.9 w/ a 33+ might get you looked at, at a few private shcools that accepts Canadians. (Think Wayne State). If you have a 3.7+ and a 35+ with everything else solid and a personable attitude, you have a decent shot. It's worth applying if you know which schools actually consider Canadian students.