SchnuppiLilac Using Q3 and HS, is it required to activate 120 Hz in both, Q3 and HS settings to fully benefit from 120 fps?
To fully benefit from 120 fps content the headset display needs to be running at 120 Hz. Just look at both the fps counter and the video info/timeline in HS. If you see 120 fps on the fps counter then the display is running at 120 Hz. If you see a frame rate of 119-120 in the video info then the content is 120 fps.
There are some examples like 6K 120 fps 36 GB, 6K Original 60 fps 88 GB. Which one of these is the better version, higher fps/lower bitrate or lower fps/higher bitrate?
It depends on what you prefer. "Better" is subjective here.
Higher quality: the lower fps one
Smoother motion: the higher fps one