I picked up a T3 in .308 for my son when he turned 12 and thus far he is 15 for 15 on one shot stops the last 4 years. Granted our Texas deer are about half the size of your Canadian deer but the .308 should be great for both. I would say my son shoot's about 40 rounds at t he range a year from 100-400 yards to practive using the Nikon Buckmaster scope with BDC reticle I put on for him. amazing how quickly he picked up on using the bDC reticle as a POA. It was so much easier teaching my 12 year old then his 75 year old Grand Pa who is a iron sight fan but again, 75 year old eyes.
I"m sure my son wouldn't enjoy those 40 rounds as much if the rifle was a 30-06, even though I think it's probably the best one rifle for everything cal. you can buy.