i think people have just had troubles with them breaking when they do jumps and what not since the core was thinner that it should have been. but for boxes and rails i think you should be fine for awhile on them.
I rode nine lifes last year and loved them. Super light, and fairly stiff. Rode them hard on rails all season and the edges held up pretty good. As for breaking them, a bro at my resort with the same skis landed really backseat off jump and snapped the tail of one ski.