I could never get on with 60 Hz either, as could see a very distinct strobe/flicker, so I think it is very much eyes dependent. One thing worth saying is that if you try it in WMR Home then it tends to look the worse, as that has lots of white background colors and tends to emphasize everything wrong - sometimes in-game in IL-2 and DCS the 60 Hz sort of looks bearable.
OpenXR has added an additional reprojection mode for sit-down sims, in that you only need to get to 30 fps for it to reproject up to 90 Hz native. So it sort of goes 30 / 45 / 90 as the ratios of what algorithm to use, if any. It’s not perfect but it really helps slow frame games, so hopefully DCS, XP and IL-2 will make that API switch as other new titles come online and use it.
Also, one thing I missed in previous post - this provides a nice explanation of where the settings have gone for WMR for SteamVR - they are effectively use the SteamVR app as the UI for their driver. WMR is doing the reprojection and leaving SteamVR to be the ‘resolution selector’ and on/off settings store per app.