A timely question, Ted, because I can offer you another anecdotal data point.
For many years I stuck with 23" 1080p screens. Then when covid confined us to barracks, I got myself a budget AOC 31.5 inch 1440p. The screen seemed huge and there was a welcome increase in real estate. Because the increase in screen size and resolution sort of cancelled out, I found the AOC no more difficult to use with standard apps than the FHD screen. However, although I could now display larger images, they didn't look any sharper.
Recently, over on the DPR medium format forum, an enthusiastic poster there waxed lyrical about the wonders of his new 6k monitor for displaying his medium format images. He also said that anyone shooting medium format had to have at least a 4k monitor. Inspired by his rhetoric, last week I purchased a 32" 4k BenQ 3280U (i'm looking at it now).
Given that the increase in pixels for a 12" x 12" image area is about 45%, I was expecting a small improvement in the crispness of the rendition (I expected nothing like the improvement promised by my ebullient and over-enthusiastic friend). And that is what I got. When I inspect images on the screen they have a small but visible improvement in crispness, punch and fine detail. Especially evident on sharp lines which look a little clearer and cleaner. Like all of these things on the 'ole web it's easy to get carried away and describe them as "ground breaking" and the like, when once you have calmed down and returned to the real world, you realise should be corrected to "just noticeable". I appreciate the modest improvement, but I don't think it be a large enough a difference to make me mourn it had I to return to my old 1440p monitor.
Although I find the improvement in the display of images to be modest (although welcome), I have noticed an unexpected benefit. The new monitor is proving more helpful while editing that I was expecting. I am noticing small editing flaws more easily than with my old monitor that need to be fixed. That's a bonus.
1440P and 32" is a good compromise, IMO. 4k kind of an improvement, kind of worse. I find 24" type FHD monitors are still sharp enough for general use but once you get used to having more screen real estate, they do seem a bit cramped.
4k comes with a cost, though. Text and screen chrome elements render too small for my taste. I tried to compensate by boosting font size in those apps that allow it but it wasn't too long before I gave in and engaged the operating system's 125% scaling mode. I reckon 4k is sharper but a 40" monitor size would be better.