It gells with my experience of Sony - they (and Minolta) always had a good grasp of colour and paid a big price in the high ISO obsessed market back in a900 days; there was a good step up with the release of the a99 and RX1 and again a step forward with the a7r, for colour representation. Sony mentioned it but few were listening.
You see very little chat about colour, many shooters don't rate colour highly, or perhaps don't see it very well, compared to say, the noise fetish that underlies ETTR. You need to 'care' for colour, as intimated in the video, keep it in a large space to prevent clipping and compression, and don't push it around too much! Once it's gone, it ain't coming back.
Being purely a colour photographer, I would not use a non-Sony FF camera. Allied to the greater tonality at base ISO due to the super dynamic range, they are now very good. A lot of the more perceptive ex-D800 and ex-5D landscape shooters are finding that out right now as they migrate across to the better, well-balanced colour of the Sony FE platform. Clients notice too..
Agree re space volume, and see how the very broad a7r gamut wall stays fairly equidistant from the Prophoto space gamut wall as the framework turned around?
I would never save worked keeper PS files in a small space any more than one would save a flattened (non-layered) master file - sRGB / aRGB files are immediately apparent as different from larger space files. It's a shame to have to crunch them down for output.
Gamuts for printers will improve over time as will displays, and that fine-graded colour at the extremes of the tone range really enhances an image, makes it less coarse, less compressed, more natural. Thanks!