Peeto, with all due respect, you have no clue what you are talking about.
The human eye's resolution is about 1 arc minute (1/60th of a degree). At 10 feet distance, 1 arc minute equates to 0.035" or 0.09 cm. With a 100" diagonal screen (about 90" or 228cm screen width), that equates to about 2500 pixels across the screen that your eye can see. And, about 1400 pixels vertically. Beyond that, your eye cannot see any more - it is simple trigonometry and vision.
True 4k has about 3800 pixels across your screen. And, about 2160 pixels vertically. You can only see 2500 of them across at 10 feet and 1400 of them vertically at 10 feet. The rest are thrown away by your eye. That's only 3.5 million actually seen of the 8 million generated by true 4k.
Pixel-shifting 2k puts about 3800 pixels across your screen (diagonally). And, about 1080 pixels vertically. That's about 4.2 million pixels generated by a 2k pixel-shift image. This is still more than what a human eye can resolve.
Luminated67 and my visual comparisons between a true 4k and pixel-shifted 2k image simply confirms what mathematics proves.
This data is for a 100" diagonal screen at 10 feet viewing distance. You say that you are even further from your screen. Good luck seeing the difference.