Just my .02. As a guy who does actually own a tournament inboard.
What is stated up above is all pretty much true. 1990 - 1994 Mastercrafts...specifically, the ProStar 190 are still highly sought after boats due to the excellent slalom wake. If the boat that you are looking at has been well taken care of, as in annual maintenance, routine impeller changes, and specifically, winterization so nothing has frozen and cracked, the boat will be reliable and capable of delivering many more hours of use and enjoyment.
A tournament ski boat makes an OK family boat depending on your expectations. If you like to tow A LOT, skiers, knee boards, wake boards, and tubes then it's pretty good. It's not good at cruising long distances across the lake in choppy water.
And you do need to become proficient at driving one. They just drive different than a stern drive because there's no directional thrust. The rudder turns the boat and the prop drives it separately, not together as one unit (like a stern drive.) They also back differently. There's a trick to docking them where you bump it in and out of gear, then bump it in reverse to get the stern of the boat to creep up to the dock.
Machine wise, they are pretty simple. There's no bellows or out drive to maintain or work on. It's usually just a big V-8 engine coupled to a transmission and a prop shaft that goes through the floor. It makes it easy to work on.
Good luck!