@ kurry:
The beta comes with a new virtual monitor that is also useful if you just want to play in immersive screen mode. Massively simplifies handling of resolutions larger than your actual monitor allows since it has all relevant resolutions predefined. The virtual monitor also always automatically runs at the refresh rate of your headset, which as an added benefit reduces judder when using the desktop viewer.
BTW: For DX9 games on Windows 11 the beta is more or less a must. The regular build has severly reduced DX9 performance on Windows 11.