I have schizos on my K2 extremes and I love them. Never had a problem. I suppose its just like regular bindings..some people will have horror stories. I think people who haven't ridden then are skeptical because its a very different binding setup but I think they're very solid.
The problem isn't durability but rather why you'd want to move them back in the first place. Those skis aren't going to be good for powder even if you do move the bindings back. Id get a pair of marker griffons or jesters and mount it 2.5cm back from true centre if you want to do all mountain riding and park. If its just park stuff and hard pack all mountain riding then mount true centre and get something with a different flex pattern (and maybe fatter) for powder.