White water has the reputation of being a real bear to shop out, but I found it to be surprisingly easy.
By the time the 90s rolled around, B/W was really good at engineering the most important things to be modular, and mostly accessible without having to strip everything away to get to what you want.
My biggest PITA game to shop was Earthshaker. This was made during the time when games were getting exponentially complicated, but Williams had yet to really figure out how to make all the parts modular and easily accessible. Simply changing a flasher bulb under the main ramp means you have to remove the upper VUK, the California/Nevada divider, and all sorts of ridiculously hard-to-reach screws and nuts along the way.