Two off the top of my head...$300 to $400 less when it comes time for new tires...and you can blow through the toll booths on the north Dallas at full speed instead of having to slow down
The benefits would be: i run 315/70/16's with a 2" spacer and i sqeak through the drive through banks, Cost-like the reply before me but $500 cheaper at tire time- i can have it aligned at any shop rather than a big-rig/RV shop, less friction=better milage. i might be able to rotate tires without taking them off the rims, and the list goes on.
I have the option of getting a pretty good deal on a DRW also but dont really have the need for it, so I am also interested in this thread. How much would this conversion cost, if possible?