The bee's actually do not consider it a barrier. They will move through it WHEN THEY HAVE THE NEED. They like to have honey a pollen right near the brood nest and will put it there until there is no need and then they will move up, if they have something to put up there.Personally I would be running two deeps or the equivalency there of no matter where I lived. Why limit the brood chamber?
The old logic was when a queen lays in your super it darkens the comb and in turn your honey. Thus the queen excluder was born. But bees don't like excluders and will consider them a barrier unless coaxed or there is a good flow on. So each must decide which way to go, neither actually hurt anything. IMO