... I think this may mean that it is possible to set how many channels to actually record on the HyperDeck Studio Mini.
I can confirm that this is the case. I made a couple ProResHQ recordings last week using the Mini; one configured for 2 audio channels, the other configured for 4 audio channels. Back on the Mac, each recording had a single audio stream containing the correct number of audio channels, respectively.
Also verified, the Mini plays back externally authored content with only 2 channels of audio (no need to pad it out to 16 channels, as I've read one has to do with the other Hyperdeck Studio models).
For playing back 4 or 8 channels of audio (ie. using the BMD SDI-to-Audio mini converter), it works equally well whether all the audio channels are in a single stream, or if it's one audio channel per stream.
Cheers,
Ken