@DW You asked about my throttle delay comment. According to my engineer friend who designs computer driven control systems for many industries including aeronautics . . . The PP upgrades have helped a lot, but if you are still using the PP servo to drive the throttle, the servo is very slow compared to the engine integrated servo in the ZO boats. (this engineer timed the PP-Servo on his CC boat before he traded it for a ZO CC). The affect of the slow PP-Servo depends on the percentage of throttle increase that is required to offset the pull by the skier. A bigger engine and/or a lighter skier require less throttle travel so the amount of servo delay depends on those factors and the settings that are in use.
Bottom line, the difference in speed between the PP servo and the servo integrated into the ZO engine can't be programmed away. The degree of it being a noticeable difference depends on the skier, the engine, the settings and probably other external factors.
All of that said, many good short-line competitors practice behind upgraded PP boats and ZO boats and say the difference isn't significant for them.