[noggin]

So what does this mean - HDR on Amlogic under CE won't look good? Then what is the point of HDR?

No - this is to do with HDR content replayed on SDR displays, where Kodi and/or the OS has to do tonemapping from HDR to SDR - which is a lossy process as you are taking a wide colour gamut and dynamic range and squeezing them into a narrower gamut and narrower dynamic range. How you approach that problem will give you different results visually.

Often people expect the UHD HDR movie converted to SDR to match the same movie mastered in SDR HD, and are then disappointed when they don't, and the HD SDR master looks nicer. The reason for that is that the HD SDR stuff was separately mastered and optimised for SDR. And HDR->SDR 'one size fits all' conversion doesn't have the same creative input from a colourist...