Not trying to "defend" my purchase I swear (lol), but this review seems a lot more positive on the KU6300's HDR capabilities than RTINGS, although it still acknowledges that the TV is limited in this regard:
http://4k.com/tv/samsung-ku6300-rev...-un60ku6300-un55ku6300-un50ku6300-un40ku6300/
Key portions of the review about HDR on the KU6300:
Again, this review still doesn't love the lack of full HDR support, and lists it as a negative. But the text of the review delivers a much more nuanced overview of the TV's HDR capabilities and seems to support the argument that it is basically HDR-lite, as opposed to RTINGS which is of the opinion that the TV does not benefit from HDR very much at all.
I don't pretend to know who is "correct", just thought it interesting and worth sharing.
Loving mine, blown away by it