[Eklar]

Do you have any sense of what does a better job at downmixing, AVR or KODI?

That topic is a whole can of worms. But there shouldn't be any difference, except in some situations where RPi/Kodi messes up the decoding in software - which I guess is possible with beta builds.

PCM is essentially uncompressed DTS HD-MA or TrueHD (which use lossless compression), and thus should be identical. PCM is transferred digitally to the AVR so the DAC in the AVR does the final decoding, thus there shouldn't be any difference in audio quality due to noisy electronics in the RPi or cabling.

Bottom line is that the only difference is that bitstreaming makes your AVR DTS blinkenlights go, and I think we're all suckers for that

Regrading DTS-HD bitstreaming, is this a pure hardware limitation or are there any licensing issues also?

My understanding is that it is a hardware bandwidth limitation of RPi, but would be nice to hear from someone who has more than google research as source