I'll jump in the fray:
2015 Nautique 200: a bit more expensive, but very used to it from our local club and tournaments.
1) is it worth the extra money?
Yes
2) If I get a closed bow, will it not work as well as a family boat?
Closed bow works fine for family boat. Lots of storage up front. I think open bows are overrated for this size boat. Too small to be safe when at speed, catch waves too easy and most importantly ski like crap if someone up there.
3) is this the gold standard?
Yes, for ease of driving and tracking. Check the "What's wrong with CP" thread, even the CP guys say it tracks better. For wakes they are all very, very good. Complaining about any of these for slalom is whining.
2015 Mastercraft Prostar: (current first choice)
1) Only skied behind it twice. Seemed great at 22' off. Should be good at long line and slower speeds.
It's good but my wife prefers Nautique, 26-30 MPH, she won't turn down a ride behind either though
2) Is it very loud? Didn't notice.
It's louder than the Nautique and CP. The MC guy on our lake, injured so not skiing, said "My boats loud" when it went by. Not bad, but louder.
3) Are the trick wakes inadequate? My son is starting to trick.
The MC guys on my lake are elite trickers and they do fine, as do lot of beginning/intermediate trickers that come to train with them. Whole lot of little gas cans filled with lead shot in there though.
4) Is the wake too wide? Is the boat too strong? (things I've heard but can't confirm).
Too wide? Seem normal to me. Too strong, what?
5) How well does it track?
Tracks very well, just not as good as Nautique. CP twists and easy to get in rhythm, MC slides. MC is different, but if its yours you learn and get used to it.
2016 or 2017 Malibu TXi
1) Any reason not to get this one? Seems good all around.
Not much experience with it but few tourney rides seemed fine. Seems a little tighter inside.
Centurion Carbon Pro
1) Skied behind it once. Seems nice. Only closed bow. How well does it track?
Tracks very well but need to drive it, counter a little and so forth. Not much but needs to be done. Very nice boat.
2) Trick wakes?
?
Straight up all the above boats are damn fine boats. Given my choice with a rookie, less capable driver or timid driver I will take the 200 every time.