I've seen it with my own eyes.
It's a nice bump, but it's not incredible.
And that's your personal opinion.
This thread, and all these threads, are going to be plagued by people saying, "X res --> Y res doesn't provide a noticeable difference," when what they mean to say is, "My display doesn't easily demonstrate the difference, I made the comparison on my phone screen, I'm not really looking at the details, my eyes aren't very good, etc."
You see the same thing in framerare conversations. People have different sensitivities, so we should avoid making blanket statements.