Okay, here we go. There are four versions of the 9C:
CAPS-Has capability to transmit either a standard FM or PCM(Pulse Code FM) signal, set up primarily for aircraft with ratchetting throttle on left stick
CAFS-Transmits only a standard FM signal, set up primarily for aircraft with ratchetting throttle on left stick
CHPS-Transmits either standard FM or PCM, set up for helicopters with non-ratchetting throttle on left stick
CHFS-Transmits only a standard FM signal, set up primarily for helicopters with non-ratchetting throttle on left stick
All versions have the same programming and mixing capabilities. The CAPS/CAFS default to aircraft programs, while the CHPS/CHFS default to helicopter programs
The only difference in the Synth version is it has a synthesized frequency module that lets you dial in a frequency instead of changing modules to do so.
Is it better? Not really. It's lower priced and has a few less bells and whistles than the 9Z, but it has the CAMPAC system of changable memory cards for more models as well as the any frequency capability with the changable frequency modules that the 9Z may not have. You will have to check on that part.