Regarding the breaking of quad-view. I downloaded the file provided by Sandboxcode and swapped it out. I'm on a 13900k and 4090 and previously, with a superb image, I none the less got the micro stuttering/jerking of objects on the ground as I looked out the cockpit left/right at low level. It would be apparent to a diminishing degree as I climbed higher.
With the file-fix in place I went into my game, no jerky foveate box (but visibly working), fired up Mig21 Free Flight and...WTF! Not one iota of jerkiness. Smooth as silk, flawless. I don't get it...did ED fix something else while also breaking the other bit?
I run the Pimax client, Pimax-OpenXR, Quad View and QV Companion, no XR Toolkit (don't see any need for it).
Serendipity in action. Though now I'm scared the fix on its way from ED might bring back the jerkiness. Right now it's pure 100% perfection.
FWIW.