In the days of old, when Knights were bold, and the King's word was law..... I had an 18' Skeeter w/150 Black Max, 24p for fishing and a 19p cupped for skiing/tubing. Didn't have a hydraulic jack plate so it was a pain resetting the motor all of the time. I'm particular about all out performance when fishing; even with scribing the original position, it never seemed right after changing.
My humble opinion - I would go with a ski boat if I were more into skiing than fishing, you can fish off of anything. If I mostly fished (and I do), you can ski behind anything that has enough power to pull you out of the water.
I've met very few that owned a dual purpose boat that would say they are completely happy with its performance - there is always something you have to put up with. But then, everyone I know is an extremist!!!
Good luck and best wishes!