Note also that reports have the CATSA opt-out patdown as being the "old-style" patdown - especially for flights not bound for the U.S. YUL tends to have a bit more attitude than screeners at most Canadian aiports but they're generally a million times better. You shouldn't have any problems, even if pulled for the scope as long as you were ok with the old patdown. As many posters have mentioned if you choose not to fly you can walk away at any time without penalty.