@danster:
Hi Sempler, can you give us the benefit of your obvious knowledge ( and thanks for the December chat link) on the issue of monitor size?
In my case its a single monitor only for BMS ( as opposed to FPS games) at about 18 inches away. It certainly doesn’t seem to be the bigger the better so I’m inclined to go up from 23 inches to 27 inches max.
Regarding how close you can get to a monitor, it really comes down to PPI (pixels per inch), and the distance at which individual pixels become indistinguishable. Apple coined a term awhile ago called “Retina” to describe a higher density of pixels and optimizing it for closest viewing distance in their displays, trying to bring attention to this concept for their line of “Retina” displays. But it applies to any display. Hard to test when most everything is web-order these days, but you’d try to use what you have now, and gauge from that what you want to purchase. For me, at 1080p 24", anything over 16" away and I can’t find the pixel grid even if I squint. Something so fine is going to come down to you as a user specifically, and then to all users of a similar model in a more general sense.
PPI is calculated by a few complex steps, best to use an online calculator if you want to play around with it and see what you have now, and what a new monitor might have, and try to gauge what would work for you:
https://www.calculatorsoup.com/calculators/technology/ppi-calculator.php