I know this much: 2-rail scale home layouts are much more common than 2-rail tinplate O gauge clockwork layouts. I would be surprised if a half-dozen of those exist in the U.S.
Back on topic, quite a few years ago I was fortunate to be a guest at a phenomenal 2-rail O gauge home layout in the Kansas City area. Appalachian coal-hauling railroad with a functional CTC machine and trains operating flawlessly through beautiful scenery. Very impressive. Although I concentrate my efforts in a different niche of this hobby, I can certainly appreciate the work that goes into a well-executed layout like that, as well as the other layouts pictured in this thread.