The Z box works great with a fairly similar feel to ZO, at least on a drive by wire boat. If you already have a PP setup it is just plug and play with the exception of mounting the GPS puck.
We did struggle with the Z box on a 1999 Nautique. I did the plug and play upgrade to Stargazer prior to the Z box coming out. Everything worked just as expected. When I added the Z box, our group almost quit the sport. Not sure if the servo wasn't working properly, or there was too much delay in the throttle, or what. We were consistently skiing one to two passes worse than we did before.
After removing the Z box ( and putting it on my DBW boat) everything returned to normal. That boat skis great now.
Hopefully this is a one time thing, but thought I'd let you know