I have travelled with similar-sized Patagonia duffel bags (45, 55 and 60L) and backpacks (45L) on several occasions with BA and never been challenged or had any issues. To be honest, I think they are a lot better than the giant suitcases a lot of people get away with bringing on board, as the duffels are soft and compressible. I frequently find that people bring very rigid and hard suitcases on board that far exceed the stipulated dimensions.