Yeah, I ended up watching that one after the other article mentioned it.I think one guy said it is there but its not noticable, you have to really look for it. You can only see it if you're doing the dimming test (or playing pong) but he said it was fairly hard to distinguish between OLED. He did mention something about a weird pillow impact on the kindle app when in dark mode but its likely software. I suppose you may have to go in store and try it out... The vast majority of them showed a comparison between mini led and lcd but they mentioned you cant tell on camera. Kind of like watching an advert for super duper amazing OLED tv on a crappy TV, you can really see it
I would imagine that grey is because the backlights all have to be on for the writing, as clearly the dimming zones are far bigger than the stroke of a character (they look to be similar in size to the full width of a character in fact).
Also looking at that pong demo, if that's the size of the dimming zone I'd imagine stars, for example, will look dreadful.
Hmm. I don't think it is a match for OLED.