Not an RST owner, but 2019 Yukon Denali so similarities should be consistent. So far the 10 speed has been an excellent shifter, but like all modern vehicles it is always trying to shift to achieve 1,500 RPM. At a minimum I'd suggest driving in tow/haul mode for better results. Much of the time I drive in "L" (used to be "M" in previous years). HOWEVER, with about 2,000 miles on it I'm having an occasional harsh shudder when the transmission shifts from 1st to 2nd under medium throttle. light throttle and floored both are fine. I've been having key FOB issues since the day I picked up the vehicle. The issues seem to be just with FOB 1, 2 works OK. Also having erratic behaviors with the infotainment system, but suspect they are related to the FOB issue so need to address things one at a time. The improvement in ride between your '17 Premier and the 19 RST are most likely due to the magnetic ride control on the RST - it does make a big difference. When I ride in non-magnetic Suburbans and Yukons I can't believe how harsh and bouncy the rides are. My Yukon does not have a rough idle, smooth as I'd expect. Overall a good vehicle, but having the same issues as many with a 2015 onwards...