Hi Doug,
I have never used an MSR Stove, only Coleman and Primus liquid fuel models so I do not know what Canadian unleaded gas would do to an MSR? The British tourists I met were unwilling to take the chance as they was no option for a replacement in the backcountry.
In an emergency I would use auto gas in my Coleman and just replace the generator if it became clogged, I think that would fix any problem?
Mike