Our 2500HD diesel pulls just fine. However, we go through the mountains and on some of the grades if you lose a back tire it is going to be exciting. Having 2 extra wheels back there provides just a little extra security.
When I go to Nebraska and other places out west and the semis come blowing past at 75 to 80 mph their wind cushion tends to push the truck and trailer around, regardless of sway control. 4 extra sidewalls would help there also.
Now statistically is it going to happen to us ? Probably not. I never let the tires wear down, I am fanatical about having good tires on the truck. The weight distribution hitch and sway bar I use is rated beyond what I need (not enought to bend a trailer frame but enough so there is cushion). I really pay attention when going through the mountains. And I don't drive above 65 as my truck gets its best mileage at 62'ish when pulling, that is right around 1800/1900 rpm
So since our truck is a recreation vehicle only, then yes, if I had to do it all over again, I would have bought a dually. However, at the time, the dealership knocked $10,000 off the sticker price of the 2500HD truck due to needing to make a sale so we ended up paying a little over 35 for a pretty well equipped CCSB 4x4. That was hard to walk away from.