The problem with the site you listed is that they are only testing the LG B6 which is the 2016 model. They need to include the B7 2017 models. One of the reason I purchase the LG OLED is that it supports all HDR formats from HR10, HLG, Dolby Vision. This works out great since I watch a lot of Netflict content and they use Dolby Vision while other content providers use HR10. Once HLG takes over for HR10, the LG TV will support those as well. Not sure if HLG can be patched for TVs that do HR10 I am not sure. The way I see it, HDR adds more punch then 4K and its the real reason to upgrade to these high end TVs. I wanted to make sure that I was future proof unlike my previous 4K TV.
HLG was developed to be compatible with standard SDR tvs. It's getting patched into the B6 model as well, in Europe only for now as the BBC iPlayer is the only thing that uses it so far. Sony has been updating their firmware as well to support HLG. HLG is simply a different (standard) curve for HDR to put more detail into the SDR range of the content. Basically a trade off, less definition in the highs for better definition in the SDR range.
HLG, or Hybrid-Log Gamma, is a one of the newer standards on the market, but it's an entirely different beast from Dolby Vision and HDR. HLG was developed by the BBC and NHK broadcasting networks to serve as an HDR format for live video. Unlike other HDR methods, which pre-encode the content with metadata to properly display the HDR effect, the HLG system is designed to work similar to regular broadcast television. It simply includes additional information regarding the HDR effect that compatible sets can implement. The broadcast is also backwards compatible with older standard dynamic range images should the set not offer HLG compatibility.
While HLG is still years away from any mainstream rollout, there’s nothing about the spec that would prevent any HDR set from offering a firmware update to support it later on.
HLG is not an improvement. It won't take over HDR10, it's a compromise for tv broadcasting that works on both SDR and HDR tvs.
The real upgrade will be Dynamic HDR, but for that you need HDMI 2.1 No current tv on the market is future proof. (And after 2.1 they'll think of something else, so don't worry about future proving)
Dolby vision is indeed the better format with upto 12 bit and 10k nits peak brightness, however the irony is that OLEDs are the least suited to high peak brightness and can't even get close to the peak of 1k nits of HDR 10. Plus 12 bit panels (or video) don't exist yet.