I have ridden PotC dozens of times since the boats were changed out. You get more wet now, without doubt. But more wet means more than almost not wet at all, not soaked. I have never seen a person get soaked with the new boats. I guess it is possible if you have really heavy people loaded in just the wrong way but that would be a result of the heavy people, not the ride. The same has always applied, even with the old boats.
You also get hit with splash from the water cannons, but you do not get soaked - or anything close to soaked.
As for getting knocked around - you don't get any more knocked around than before. No one has been thrown from a boat. If it was a realistic possibility, it would have happened by now.