In BOS, for AC flights out of Gates B1-3, the duty free store is pre-security. Oops. On the plus side, there are no full body scanners there.
In YYZ, going to the US on UA/AC in T1, you get to carry your duty free out of the store so no need to worry about buying early enough before the flight (this is a good thing)
And how is it that a Canadian whisky costs 7.5% less in ORD vs YYZ duty free store, when it’s made in Canada!? Makes you wonder which duties are “free” exactly.