I installed the ski module on my 2016 GTR215's using the instructions that came with the ski module kit. It took about 30 minutes on each machine and that was in non-ideal conditions down at the shore, not in the workshop.
Works OK for wakeboarding and skiing but is trickier to use than a speed control on a full size boat because the launch ramp setting is not quite right. Its like its too linear. I would not suggest it as the best way for a beginner to learn, but it is tons better than trying to learn behind someone driving with manual throttle on a fast-responding PWC.
The one drawback I have experienced a couple of times is that it sometimes is not in ski-mode when you expect it to be. A full throttle pull on the 215 is quite the shock to the poor kid on the other end of the rope.
I don't have the cruise switch on my GTR215, so I don't have a comparison between cruise mode and ski mode. My next project is to add the cruise switch. Per the instructions posted above, the factory handle cruise button parts can be swapped in to also get cruise mode.
I know, I should have just bought the wake-pro to get those features, but color choice and the availability of a couple of demo units at a great price entered into the decision.