And we are looking forward to you coming over too
Air Canda ticket LHR-YYZ = 3,546 miles (eac way) There is no CoS bonus for J on AC intl tickets. So if you can get more than 7,092 miles with BMI then I would go for it.
I am not sure if you book the flight on BMI (with BMI flight number) but it is flown on AC metal if you earn your extra bonuses. Someone here will know