You might want to check this review at babeltechreviews.
Its, a good guess, - but I assume what seems strong there (for VIVE, Index) will be better also for the 8KX, but look for yourself, they have nice Diagramms for Frametimes, Droped and Synth:
VR Wars: The RX 6800 XT vs. the RTX 3080 - 15 games benchmarked (babeltechreviews.com)
Mixed summerzied it (source AMD Radeon RX 6800 XT im VR-Benchmark (mixed.de) ):
| Titel | Einstellungen | RX 6800 XT | RTX 3080 |
|---|---|---|---|
| Assetto Corsa Competizione | VR High | 126 | 138 |
| ARK: Park | Highest + 200% SS | 175 | 267 |
| Boneworks | Highest + 160% SS | 210 | 190 |
| Elite Dangerous | Ultra | 141 | 148 |
| Fallout 4 VR | High | 152 | 145 |
| Half-Life: Alyx | Ultra + 200% SS | 145 | 158 |
| Hellblade: Senua’s Sacrifice | Highest + 170% SS | 96 | 109 |
| Into the Radius | High + 110% SS | 135 | 151 |
| No Man’s Sky | High | 108 | 126 |
| Obduction | Epic | 112 | 130 |
| Project CARS 2 | Highest | 123 | 117 |
| Skyrim | Highest + SS max | 134 | 158 |
| Subnautica | Highest | 110 | 102 |
| The Vanishing of Ethan Carter | High + 200% SS | 250 | 258 |
| The Walking Dead: Saints & Sinners | Highest + 150% SS | 116 | 120 |
Edit: added the tables for 3090-3080-2080TI