The first statement is not true at all. Yes, you can get wetsounds to now fit in the factory locations but you can also get bulleted cans with car audio speakers as well. NVS speakers will fit on the cross piece but not in the factory locations.
The wedge works for sure. He should get the power wedge which helps shape the wake better depending on your preference and if you're surfing or wakeboarding. If you use a lot of ballast (2-3K) then you probably won't want to use the wedge. With only stock ballast though, it really helps peak out the wake.
The 247 is an awesome lake limo...I mean boat! He won't be disappointed at all. The seating and storage are amazing. For huge wakeboarding wakes though it will take a lot of extra weight. I hope this helps. He should check out www.themalibucrew.com