I just spent the evening messing about with my Xbox (playing some games in HDR, no SDR yet) on the Q90. While I am not making a final judgement about the overall quality of the TV based on just a few hours of uncalibrated usage, I can already confidently say that the so called improved game mode on the Q90 is much ado about nothing, at least where those of us with the 75" Q9 are concerned.
So rest easy 75" Q9 gamers. You really aren't missing out on much of anything. The differences are negligible at best.
82Q90R / 75Q9FN / Denon X6400H / Polk Audio LSI 7.1.4 / Nvidia Shield / Panasonic DP-UB820 4K BluRay / Xbox One X / PS4 Pro / Nintendo Switch / Custom Gaming PC / Custom VR PC / HTC Vive Pro HMD (Wireless)