Reason for 4wd is I plan to do a lot of desert trips. Sad and mud is no bueno when you have a 10k lb trailer behind you. Not sure I want a dually. Stopping power seems great, but being wide as shit kinda sucks.
We had the 2500 version of the dually in 4wd before this (same truck, without the second pair of rear wheels) - I did have to use 4lo to get a 2 car trailer out of a muddy field in Newfoundland, so it was certainly useful at that time, but I think the low first in the dually probably would have worked for that as well. The 2500 scared the shit out of me when stopping that trailer, however.