Gaming on my oled is far superior than on the dx902, gaming is where the dimming/blooming shows its face, but in every day content, TV shows/films I very rarely see any blooming.
I have the opposite experience; i never notice any of the backlight related issues when gaming, they are there of course, but i never pick up on them, whereas with films i always notice the dreaded backlight banding on panning shots.
Interesting to hear you mention Gears 5. That scene with the light illuminating the dark tunnel looks near identical on the 902 verses my oled. The dark is rendered above black on both sets, it's never completely black, even with the in game brightness set to 100. I actually found that scene more impactful on the DX due to the flashlight looking noticeably brighter, and i never registered any blooming (although i'm sure it's there)
In fact i rarely play games on my oled, as i find the hdr impact lessened on the majority of games i tested. Forza horizon 4 was eye opening for me; the hdr skies, which are the visual centerpiece of the game, looked significantly different on the oled; much, much dimmer, almost reminiscent of an sdr image (i assume that's the abl kicking in, as those skies are super bright and take up half the screen)
One thing i have noticed is the dimming on the 902 can be a bit too aggressive, sometimes rendering parts of the image as black when in fact they should be above black.
In the first Matrix film in hdr, near the beginning, Neo wakes up and is infront of his computer. It cuts to a shot where we see the back of his monitor, and on the DX the left side of the monitor is completely black, even with abc on min. This causes problems on my DX, as the black sort of flickers between complete black and splotchy grey patches.
I tested that scene on the oled, and the back of the monitor isn't black at all; not a hint of black to be seen. I think the oled is rendering that correctly, and the DX is being too aggressive with it's dimming.
In fact i use my oled almost as a reference monitor. If dark scenes look off on the DX, i compare it to the oled and make adjustments to see if i can match them up. Currently running the ub 820 player with system gamma +2 in the hdr optimiser menu, which has really helped with dark scenes on my DX; Neo's monitor is no longer black with that ugly flicker gone and looks closer to the oled, and the last half of Jurassic world fallen kingdom, which takes place in a dimly lit environment, looks much better now.