Spent most of yesterday sorting through all the crap that came out of the old truck, throwing half of it away, and putting the rest back in the new truck. You know, all the stuff you do when swapping vehicles. Took a look underneath and everything looks excellent. All of the filters look recently changed. Spare tire is original, so I'm thinking about replacing it for age, even though it's never been on the ground. The rest of the tires have 2023 date codes, and are nearly new by the tread depth. Lucked out there, 'cause the dually was going to need all new tires this year, so that saved me a bundle. Usually I manage to put brand new tires on a vehicle right before selling it.
This morning I took the new truck on it's first highway run, taking my wife to the airport at zero dark thirty. Having made the same basic trip before (to Tucson and back) in the old truck numerous times, it was a good direct comparison. Suspension... HUGE improvement in ride unloaded, just as expected. Unloaded, it rides better than the dually did with 1000lbs in the bed. Gearing... In the dually, 1900 rpm (what I liked as max cruise rpm on the 6.7 Cummins) was ~68mph. The speed limit on most interstates out here is 75mph outside the cities, and the cars run 80+. I generally just set the cruise at 68mph and sat in the slow lane and let the world go by. In the 2500, 1900rpm is over 80mph, so I was able to set the cruise at 78mph and still get the rpms down into a more efficient range. I was very surprised that the 2500 averaged nearly 3mpg better than the dually... running 10mph faster on the highway. The dually would typically return 15-16 average and the 2500 was 19mpg for the 160 mile round trip.
After I got home, I hooked up the trailer for a test drive.

First up, I was happy to see no visible squat with the trailer hooked up. I'm often surprised how much squat some newer 2500s have with trailers that aren't all that heavy. I knew I would be giving up some stability with the shorter wheel base and single rear wheels, but it wasn't at all adverse. The dually was so stable, the extra weight under acceleration and braking was the only thing noticeable... otherwise, you'd never know there was a trailer back there. You can definitely feel there's something back there, mostly on pitch undulations, but it's certainly liveable. With the different gearing, towing from 55-65 will probably be done in 5th gear with 6th locked out. I do need to re-calibrate my trailer backing geometry for the shorter wheelbase, but it will be a net improvement in maneuverability.
Definitely pleased with the trade at this point. Increased our road trip comfort, speed and economy; and the 2500 is more than capable for our current towing needs. The out of pocket cost to trade was less than I would have spent on tires and re-gearing the dually, and that doesn't even consider what the suspension improvements I was considering would have cost. Even though I was used to dealing with the dually around town, and it didn't really bother me, the 2500 is definitely better for navigating tight parking lots and traffic.
I was initially somewhat hesitant about trading off a perfect truck that was paid for, but I think I may have ended up with an even perfect-er truck. And it's still paid for, though it did cost a bit out of pocket.