Jack wrote:

Cub Cadet's ZT lawn tractors are considerably more expensive thanCub
Cadet's lawn tractors of the same size but without ZT capability.
Are they worth the higher price? Do they save considerably more time,
and presumably more gas to make them worthwhile?

The ZTs certainly save a lot of time when mowing relatively large areas.
They cost a lot more because the drive system is a lot more complex with
more expensive parts than a basic gear transmission. Certainly the fact
that pretty much all commercial landscapers use them points to their
efficiency.

If you have less than a couple acres to mow, the efficiency advantage
will begin to disappear. Another caution is that the hydrostatic pumps
and wheel motors, like all hydraulic components can be destroyed in
short order by improper maintenance and contamination of the hydraulic
fluid, and are very expensive to replace.

Sam's club has had a decent ZT mower for a couple $k, that is probably a
better deal than an over hyped and over priced brand like Cub Cadet.
I'll note that you will see the commercial outfits running mostly SCAG
ZT mowers, with some Deere and Ferris thrown into the mix, and not a
single Cub Cadet to be found.