As per Rtings:
"What it is: How many colors a TV can display at different luminosity levels.
When it matters: HDR content. Includes some streaming videos, UHD Blu-rays and HDR games."
And QLEDs as they are now are not really where Samsung is taking it. Yes, OLEDs have better picture, but Samsung seems adamant that the tables will turn rather hardly when they make the QLEDs self-emitting.
So it simply allows for more saturated colors at extreme brightness. Yet OLED TVs still take the crown when it comes to picture quality. Go figure?
As to your QLED tidbit, are you saying that an hypothetical tech that isn't remotely on the market is currently beating the picture quality of OLED TVs?
Sure enough, when it does comes out, it will be expensive, but also more than likely the better of the two tech. But until there's a consumer-ready set available, there's really no point in bringing this up in a thread where someone asks what he should get in the current age.