I wouldn't say the Canadians weren't up to producing tanks. We can't forget they were in the process of starting to build a version of the Sherman. Montreal Locomotive Works completed 188 copies of a Canadian built M4A1 to be known as the Cruiser Tank Grizzly I. I think if the decision hadn't been made to center all Sherman tank production in the US, the Grizzly would have made a good note on the battlefield.
I also think if the Ram II had been diverted to the Desert instead of being used to train the Canadians in England, i think it just have might proven effective. As stated earlier, that 6 pdr gun would have been able to handle most German and Italian armor fighting in North Africa. Even though obsolescent in 1944, the 6 pdr/57mm was still proving to have uses. Also the Ram also proved mechanically a good vehicle. I don't think you can call it an incompetent design.
BTW this is one of my favorite pics out of all my reference material...i love the Grant and Ram shown side by side...
just some thoughts