interesting... Even 60+ years ago when some were still keeping bees in skeps, it was understood that managed bees needed at least two deeps for brood nest. I wonder what kind of a) swarming problems they have, and b) what kind of honey production they have. I have an old edition of Walter Kelley's book, How to Keep Bees and Sell Honey and if I remember correctly, inside the front cover is a full page picture of an apiary in KY where the beek runs two story brood nests "in an area where most beekeepers use one deep for the brood nest..." and this beek has bumper crops compared to the neighbors. I'll have to dig that up later, and get the exact information.I run one brood chamber. I've toyed with the idea of running two but most beekeepers around me just run 1.