Great implementation, Strap! Your city is a work of art, and I like the prominent portrayal of the subway action. I can imagine doing something similar under my city...and then with hidden areas via curtain or removable wood panels. I have a fold-down river, however, which would necessitate lift-out subway sections (nothing is easy).
Does anyone recommend the Loco-sound MTH subway sets? I see some advertised now and then...what don't you get as compared to PS2 or PS3 features with Loco-sound?