Just remember the Liberals and NDP say "sole sourcing" is bad because you will end up with stuff like C-130J, Leopard 2's, C-17's and Chinook helicopters. All of which will make the Canadian military more effective and therefore we may be called upon to do more as the US scales back.
To be fair to the critics I think the F-35 is a plane to far and we should take a hard look at what we need in a fighter. My concern is that we are buying far to few airframe and throwing all our eggs in one untried basket. I would be far more comfortable with a mixed fleet of 80 or so fighter aircraft made up of Super Hornets and perhaps the F-35.