Four months deeper in … I’ve got 7 HO districts now. The latest is based on my 2009 Roco digital start set, but greatly expanded, including incorporation of a Walthers powered turntable and roundhouse. The Roco/Walthers layout is elevated above the 6 Kato districts. The Roco is under multiMAUS control. The Kato is controlled by MRC, with the cabability to switch any Kato district to analog control when I want to run straight DC trains.
The G scale is split between ESU control and analog control, again with the purpose of allowing legacy DC locomotives to run.
The grandson still prefers G scale because the figures are closer to the size of action figures, so it is easier to play with them. I loaded passengers into the passenger cars, and his main concern was that now some of the dogs that he’d assigned owners to are waiting without care while their owners ride around the layout.
The train hobby can be expensive too, but it doesn’t begin to approach the expense of high end audio. $15k can get you a very nice train room … $15k is chump change in high end audio.