Andy,
I started with a 2007 990 wet bath on my 2007 Dodge 3500 dually with 4.10 rear, stock tires, BD exhaust brake and Firestone air bags. Never needed the airbags. The exhaust brake was the best addition I ever did for my truck. When the original shocks wore out I upgraded to Rancho 9000s
My 2017 AF 1150 wet bath required the addition of lower stableloads to address proposing and some of the sway. Adding the upper stableloads smoothed out the remaining handling issues. Shortly before purchasing the 2017 I did replace the rear leaf spring bushings. There's no problem hauling over interstate Rocky Mountain passes. However, the exhaust brake has recently stopped working and I do have to really take my time down twisty turns steep grades. Normal grades are not an issue to stop suddenly, even at 65-70 mph. The west side of Chinook Pass going down SR-410 in Washington was a bit concerning. The 10% grade down Slumgullion Pass without a decent place to pull over set my brakes to smoking and burned my brake fluid. I won't take that type Pass again until my exhaust brake issue is resolved.
Also, the center of gravity on the 1150 is much further towards the rear. I do notice a little handling diff when the black tank is full. Steering is not diminished but there is a diff feeling when all that weight gets behind the rear axle. This is also something you might want to consider if you plan to tow heavy. I did move my spare to the front bumper and haven't noticed the steering sensation this trip.
Hope this helps.
2017 Arctic Fox 1150 wet bath, 510 watts solar, 300 AH lithium, 2000 watt inverter
2007 Dodge 3500, DRW, 4X4, 5.9 CTD, SunCoast 48RE, 4.10 rear, Firestone airbags, Rancho shocks, upper/lower Stableloads, Fastguns.