Great description Scott, as usual.
I haven't had any experience with that apartment house system but I have heard a lot about it. Usually people wondering why their heating appliances don't work right.
The others I have seen a lot of. The corner delta is common on those pumping stations you see along the road (all 3p L/L load). We also have a lot of red leg here, in light industrial bay areas and they usually have a 3p panel in the shops and a 1p panel for the house loads and offices.
