Regarding metadata, the Sony rep basically said the Sony's are only using the metadata to recognize that the source is HDR, and then they analyze each frame to achieve the same thing as dynamic metadata.
So to me, this makes the whole metadata thing a fiasco. We require a new standard for metadata, that no one really uses, and wasn't necessary in the first place. Now we have HDMI 2.1, which adds the dynamic metadata, and makes current displays obsolete.
I still haven't heard a good explanation on what one is suppose to do with the dynamic metadata. The only possibility that comes to mind is dynamically changing the roll-off in tone mapping. And that, IMHO, can't be good.
The fancy manipulation that the Sony rep is refering to, breaking the content into low, medium, and highlights, and processing independently, is not for me. The grader already manipulated the master the way he wanted it. The display's job is to reproduce it, not to make it look "better".