Boomerang was Moomba's first attempt at a ski boat. It was entry level in features, but was very light weight. The slalom wake is supposed to be near nothing. I haven't heard about tracking or other issues. I know very little about the Kanga.
IMO, you can get into many different slalom boats for your price range. I would look for a boat with a long history and high numbers of production. Parts for the older moombas won't be as easy to find as for MC, Bu, or CC. I would also look at MC PS 190s, Sportstars, PS 205, Bu Response and Sportsters, and CC 196/206. All are great slalom boats.
Good luck in your search.
1997 MasterCraft 205
2008 Moomba Outback
1999 MasterCraft Sportstar OB
1992 MasterCraft 205
1999 Malibu Response LX
1987 Marlin Magnum Skier