No one knows yet. But on the power wagon it makes a big difference. Gives a better ride over bumps too.
The power wagon has a SFA. So not a fair comparison. I agree that nobody knows how much of an actual offroad benefit a sway bar disco has on an IFS bronco. I think it will give a smoother ride at lower speeds if nothing else so that's a nice benefit, but I'm not as convinced it will add a ton of traction. Even if it drops a wheel 6-9 inches, that still doesn't mean it has much weight on the tire as you don't get the fulcrum effect like you do on a SFA.
I bet any trim squatch with 35s will be more capable off-road than Badlands with 33s plus disco in 99% of offroad scenarios as clearance is normally king. But we won't really know for sure until it's tested real world.