With some research done, I've narrowed my choices for DCC systems down to two: NCE and SPROG. And, it turns out that one of my fellow CZM cohorts (Jerry C.) just so happens to have some units for both systems that he is graciously letting me play with :0).
Here is my current thinking regarding the two systems ... for this discussion, I'll focus on a plan for the outside mainline throughout my module layout and including the yard district on the Central End.
For the NCE system, I would probably start with a PH-PRO 5 Amp Starter set and then add a PB105 5 Amp Power Booster for the yard district. Power supplies (P515 15 VAC @ 5 Amp) are extra. For wireless operation, I would connect the Power Pro System Box via a serial-to-USB connection to a low-cost touch notebook and run JMRI WiThrottle for use with my Android phone. The retail list price for the NCE equipment totals up as $529.95 + $159.95 + (2 x $59.95) = $809.80, and likely this can be found for a discount that should get that down a lot closer to $600.
For a SPROG system, the setup would be something like a SPROG-IIv3 driving two 2.5 Amp SBOOST units, one for the main and the other for the yard district. The SPROG-IIv3 would also serve as the programming station when needed. This combination is available as a package for a retail list of $250 and includes the necessary power supplies. The connection to the notebook would be over USB and the same JMRI software and phone arrangement used.
The fundamental difference for that over double in price is that the NCE would come with its wired handheld throttle and the NCE system offers double the power output per booster. Another subtle benefit of the NCE is that the output track voltage is adjustable within the boosters.
In this analysis, the SPROG arrangement seems to be the right choice for me for a couple of reasons. The first is that 5 Amps is rather an overkill for a Z-scale layout ... I can't see the need to simultaneously operate as many as 15 locos in a single power district. I expect that I would be running no more than a half-dozen, this presumes that at least one or two of my trains would be running with multiple engine consists.
The second is that I fully intend on running with wireless throttles and WiFi-connected phones seems clearly the right way to do this. That said, the need to have a dedicated NCE Deluxe Pro Cab appears redundant. My original thought was to use the Pro Cab at the programming station but with the JMRI solution already connected up, I would just as well use the notebook user interface.
Please note that I'm making this evaluation on the presumption that all I'm really interested in is independently controlling my trains and I've really no interest in having my layout track switches or accessories controlled by DCC. I can see accessories possibly one day (including sound decoders), but I don't see automating my turnouts as very interesting. Both systems seem to have a reasonable handle on controlling accessories.
OK, it appears on the surface the the SPROG has the edge on a cost/performance analysis. Now I need to actually try each to confirm that they meet my expectations.