No snow? Probably not worth it. However, AWD has a substantial advantage in the rain - primarily when hitting puddles, etc. AWD tends to plow right through where the front tires will hydoplane in a rear wheel drive truck.
Tim - I just got in from a run up and back to Northern Mich this morning .... at one point, there were 4 of us traveling on hardpack snow at around 80-85MPH

No traffic around to speak of and we spaced ourselves out pretty good. Just need to keep a sharp eye out for salt trucks and seniors in the Crown Vics moving at 25MPH. Thank god for quattros .....