HDR Playback (MadVR) Settings Recommendations

MadVR has additional HDR related settings other than just passing through metadata.  Is there a benefit to using the tone map or calibration settings? Or any other settings?  I experimented with them. But it didn't seem change anything.  
I'm using Alienware's QD-OLED display which has 99% DCI-P3 coverage and should be well calibrated out of the box.  

One more question:  Is there a way to adjust overall video brightness while playing back HDR video?  Unlike a TV, this monitor doesn't have any brightness control when when HDR is enabled. The MadVR setting for it doesn't seem to work when playing back HDR.

If you want to adjust brigthness, then you have to enable tonemapping in MadVR. With the peak nits setting you can adjust brightness. Lower value is brighter.

I don't have any other specific recommendation for HDR.