I have a 2WD Duramax 2500 crew cab. With the fiver, I have to be very careful about the surface being driven across. Even wet grass can make it impossible to get moving. If I had it to do over again, I would buy a 4WD.
OTOH, we've never gotten it stuck. There have been some "oh krap" moments but I was able to keep moving and get out of trouble. In the snow, the truck by itself is worthless with regular tires. But for winter, I install a pair of good BFG Commercial TA Traction tires (snow tires, really), and the difference is night and day. If I wanted to run these for towing, I think the wet grass type situations would go away.
Bottom line, I personally would not trade the truck just to get 4WD, but if I bought another truck, I would get it.