I had a hard time getting the KLR rig out of a jobsite the other day due to the steepness of the driveway and loose gravel. However, it is a light rig with a skinny tire. Basically, if I have trouble backing a 2WD pickup up a hill I have the same trouble with the KLR going forward unless I am able to carry momentum.
I think I would like 2WD in a rig for the same reasons I like 4WD in my trucks. It is there when you need it..... But I am not sold on URAL's