Avctive Traction Control & Locking Diff

I'm considering a new FJ and am a little confused about the traction systems. First, it seems that ATC and the locker can be engaged only in 4WD Low, which doesn't seem to make much sense. Next, I think that I can engage only one at a time, ATC or the locking rear. In other words, you can't lock the rear and engage ATC so that it works up front. Am I right about all this? I think the Jeep Rubicon Unlimted allows you to lock the front & Reaf diffs in either 4 Hi or Low. Thanks!