Matt,
Welcome back! Sounds like you had some downtime to think about trains. That’s great you got to Hearn’s shop! Looks like it is near a railroad yard of some sort. Did you see any Australian trains.
Personally I like the idea of Atlas track on the upper level. I use GarGraves, but either would look good because of no plastic ballast roadbed. What you have done on the lower level looks good!!