I wonder, would somebody acclimated to 6k feet or so (colorado springs), notice as much?
Probably not. While I was in the summit shop on Pike's Peak, a bunch of young men came in wearing blue track suits. I asked who they were, and I was informed that they were cadets at the Air Force Academy. Apparently there is (or was) a group training to be Ranger officers who
run up the cog railway route for conditioning!