I have mostly modern Lionel engines from 1992 and later. When I'm finished building, I'll begin running with a postwar ZW and a KW. Would it be better to invest in a modern transformer like the ZW-L because of the more sensitive electronics? I'll be running mostly in conventional until I learn the Trainmaster Command system and get comfortable with it. I do have some postwar engines as well. Thanks.
Hoppy
Personally, unless you have a serious "romantic" attachment to the ZW and KW, I would go with a modern transformer, not necessarily a biggie like the ZW-L, but something modern. The old PW transformers don't have a bell button, and the whistle button generally works poorly if at all on modern engines unless you modify the whistle circuit in the transformer. While the ZW and KW have big power numbers, their output voltage droops seriously with load, which causes dimming of lights on the layout and other things.
I have been down the same path over the past year. I started out with a V, a ZW and a KW. Plan was to use the V to give four different accessory voltages, but operating a Lionel milk car on one circuit seriously dimmed the lights on the other three, for example. They are all gone and I am using an MTH Z-1000 brick to give me 14 and 18 volts for accessories and a PH-180 and Legacy Powermaster for the track supply and never looked back. If you don't need a whole lot of power the MTH Z-1000 is my favorite choice for mid-powered conventional operation.
I think PW transformers belong with PW locos and layouts, and modern transformers with modern locos and layouts! Move the ZW and KW along to someone who wants to use them with PW equipment.
Just my $.02 worth. No refunds.