the off-road pack does add some nice features like the all-terrain tires and skid plating, which does add weight and the AT tires will have an impact on handling since it's not specifically designed for just one surface. To be fair, the tall sidewalls will give you a little more bump cushion compared to the limited's 22in wheel options but it shouldn't be a drastic difference since coming from a Passat, you'll notice the truck is...well...not a Passat and will never handle as well as one since it's 3.5 tons of metal.
I've done my fair share of aftermarket tinkering on cars in the past; however, with the air suspension and overall complexity of these trucks with the air suspension, I personally don't see an anti-roll/sway bar doing much but causing the tires/suspension to take more of the lateral load than intended/design. Not sure what it will do long term to the air shocks and CA bushings.
Outside of lowering the truck (which you can leave it in aero mode, which does help MPGs and a little handling), there's not much to make it handle better and carve corners, and at that point, the air suspension would be tossed out and cause all sorts of mayhem.
That being said, the limited's and Ram 1500's in general are some of the best, if not THE best, driving/riding trucks on the road and in the 1/2 ton class.