FWIW, I have north of a hundred of these, and they work well for me. The only minor annoyance I have is the use of Hail, which is a remnant of an old patent issue. Your mileage may vary.
The latest firmware (that I know of) for the DZ15S is 1.23. Note that the built-in firmware updater is not currently able to update Leviton devices. You will need to use a Z-Wave stick to perform the update.
