HDR raw decode settings

What raw decode settings should you use in a RCM workflow. I though raw data was mapped direct in RCM but it appears the RED and cinemaDNG decode settings get applied as well. I found decoding using camera meta data appears to work the best.
The red decode settings have options for req2020 and 2087 but the cinema DNG doesn't. Its a bit confusing that the decode gamma can interfere with the RCM gamma. A CinemaDNS mapping gamma of 2.4 causes clipping that can't be recovered where as the use camera meta on the same clip preserves the highlights.

How does the raw tabs color space and gamma setting apply in a RCM workflow where the gammut and gamma is already mapped. Changing the values does change what you see.