Excellent, looks like AC have revised the rules for checked baggage if travelling in J:
Free Allowance
Air Canada and its regional carrier allow each customer to bring two pieces of luggage in Hospitality Service and three pieces in Executive Class/Executive First, which is carried in the baggage compartment of the aircraft at no charge. This is known as the 'free checked baggage allowance'. The overall measurement of each piece (L + W + H) must be less than 62 inches or 158 cm.
In Hospitality Service, each piece must weigh less than 50 lbs. or 23 kgs (except on flights to/from Brazil, Japan, China, South Korea or Hong Kong, Brunei, Cambodia, Macau, Malaysia, Myanmar, North Korea, Singapore, Thailand and Vietnam where the bags may weigh up to 70lbs).Bags weighing between 51 lbs - 70 lbs (24 kg - 32 kg) will be subject to excess fees payable at the airport. Bags weighing more than 70 lbs (32 kg) will not be accepted as checked baggage.
In Executive Class/Executive First Service, each piece must weigh less than 70lbs or 32kg and the total weight of the three bags must not exceed 150lbs (69kg). Bags weighing more than 70 lbs (32 kg) will not be accepted as checked baggage.
So, if flying J you can still have one (or even two) pieces between 24 & 32kg, which is great news
Got to keep the total down though if you have three, which is fine. This was something raised at the LHR DO, and if this is a response to the questions there, then I for one appreciate AC for doing addressing the concern ^