However the Xr I use at work additionally color shifts to a reddish hue when viewed off-axis, and the Xs and Xs max color shift to a blueish hue. Undoubtedly there's variance in the amount of color shifting that happens between individual units, but these are just signs of differences in panel tech.
Well that a (AM/P)OLED Panel shift Color is normal.
Samsung Galaxy S8 was a good reddish shift. S9 very slight green-blue. Google Pixel 2 XL in the first batches strong blue shift. POLED adds a grain to it at low brightness. (Plastic-Substrate instead of Glass). All OLED still have degenaration of lightpower within 2-3 Years and Burn-in/Ghost-Image as well. And they are Slow as hell in Refresh-Rates.
Thats why only some TVs are done with OLED, but no Computer Monitors.
All in all, OLED technology has not yet completely outgrown its infancy.
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Many people can certainly see the difference with higher PPI.
Ok it depends of the Visual Acuity a person has, but i think many wont get better then 20/15.
I say it with a Acuity of 20/20 :
Viewing Distance : 11 inch
6,1" 826x1792
20/20 Vision = 1 Arc Minutes // 0.0002901 Radians
326 PPi Screen // max 316 ppi what the Eye can see.
next Iphone XS Max :
Viewing Distance : 11 inch
6,5" 1242 x 2688
20/20 Vision = 1 Arc Minutes // 0.0002901 Radians
455 PPi Screen // max 313 ppi what the Eye can see.
As you see, the Test person woulndt see any diffrence (ppi) at all between these two screen.
Results getting better with a Vision of 20/10, but not many have a such good Vision.