update. Workaround is to add DCS.exe to Steam game folder as non-Steam game. Then SteamVR retains settings. Only caveat is when starting the game the pop-up says "DCS is not a VR game", which of course it is, and the old stuttering game logon with the shaky splash screen and blue progress bar comes up, same as in 2.8 VR, but game is 2.9. Don't know if anyone else loses their SteamVR settings booting into 2.9 but this is my experience.