How much further is it to go the way they want? Great Circle Mapper at http://gc.kls2.com/ says 2501mi vs. 3138mi. Maybe it's worth it for the extra 1274mi R/T? And seriously, depending on when you're going, YVR might have better connection weather than YYZ.

I went through YVR to get to and from CUN once, that was backtracking too, since I was starting in YOW.

=aw