Just in summary...is everyone pleased. Is it a quality piece? I recall issues with the basic Lionel Transformer years back.
Well, I could not be happier. I posted my review of mine sometime back and you will find that and those of others by doing a serach on forums for ZW-L.
The ZW-L runs almost all locos slower, smoother, in conventional, than any other power supply I have ever seen - quite a significant difference on heavy locos with can motors, somewhat less dramatic a difference with very low powered small stuff (Superstreets) and older locos with track-power energized stators (Pullmor motors) but still noticeable.. It also has a three-level protection and breaker system described on the first page of the owner's manual that is industry leading, apparently.
There was a long discussion about the fact that the calibration 0-20 on the thorttles is mostly a legacy (small letter el) feature harkening back to the original ZWs, and that in going from 0-20 the unit actually only goes from 0-18 volts, and that the meters are only accurate within a volt or so . . . turns out the same is trume of many other supplies.
It is noticeably bigger than a Z4000, and its meters are harder to read than the Z4000's digital displays. Also, its output terminals are traditional types and don't take male connector plugs like MTH does. In all other ways it seems to be superior to anything else out there, if rather pricey. I've got one and plan to get another.