I'll add my piece to this discussion as I am one with some experience with both. I can say the 2019 can exhibit that rear dance as the 2018 but at a higher (60+ vs 40+) speed when cornering but the movement is still less than on the 2018. I have been pushing it more and more as this 2019 didn't seem to have any weak points like the 2018. While the 2018 was unsettled over most bumps and road surfaces, the 2019 is smoother. Do I want to add a sway bar, yes. Do I feel it is necessary for most of the driving I do, no. Am I in a rush to get one, nope. The 2019 is better put together compared to the 2018 and as said, KIA is known for making improvements quite fast to short comings, to make sure their customers are satisfied. That being said, on the dealership side, most could care less about helping folks to get their issues sorted, they would rather trade your car for the newer version so they can attempt to rip you off with their stupid markups.
I recently experienced the
G70 again and I really would love that suspension tuning on the Stinger. It would make for a much better driving experience. That said, as most of you have noticed I have not been on here much lately. I am very happy with my car as is, I bought the
badges and haven't even gotten around to installing them. Wish list, a quieter interior similar to the K900, suspension tuning like the
G70, a sport hybrid system so I can have better economy for the commute and the power and performance for those long road trips.
Wrapping up, my 2019 is a better put together car vs my 2018 and I suspect the 2020 will also have improvements over the 2019. Yes, I have tested it on similar roads (I drive them every day) in different conditions and the 2019 has solved the suspension issues I had with the 2018. I still have yet to drive my buddy's car, that might make me consider the sways but as of now, I have no regret in giving him the one I bought as it improved his ride and solved the dancing rear end issue he was having.