If I had the multi-mode system, there would be times where I'd use the AWD mode to improve stability and help prevent fishtailing to an extent when the roads are wet and only bridges might be icy, but most traffic is still moving 60 mph. It almost seems absurd to put it in 4WD (or center diff locked) at those times just to prepare for ice on occasional bridges.

If you don't think you'd use the AWD much, then there's some positive points to keeping things simple and not even having a center diff. Note that the part-time 4wd is functionally the same as locking the center diff on the multi-mode system.