There's always a balance and trade-off here.
2x scaling with 4k really means you end up with the same screen real estate as 1080p.
In my opinion I would very much prefer 24" or 25" at 1440p with native scaling which is ~120 PPI. I personally run both a 25" 1440p display and another 24" 1440p display at 1x. I still consider going from 1080p to 1440p one of the biggest quality of life upgrades I've encountered when I made the switch 7 years ago. It's the same level of "wow this is great" as going from a HDD to SSD.
Before there were shortages you could get a high quality IPS panel monitor from a reputable brand (Dell, ViewSonic) with low input latency for around $300. 4k at 1.5x also gives you the same real estate as 1440p but with higher PPI but I don't know how crisp that will be given the scaling ratio.
Yes and no. With much clearer looking text, I can use smaller fonts (13 -> 11 in IntelliJ) than on regular 1080p displays, so there's _some_ difference.
1.5x is nice on a 27 inch 4k with 14+ fonts. HiDPI monitors do seem to have bloom, so slightly bigger fonts with higher DPI are good to have.
In terms of viewing space this fits (4) side by side code windows at 80 characters with a little bit of breathing room.
Is that even a problem? I am not buying better screen to torture my eyes. IMO. A smaller sharper text won't really be easier to see compared to a larger but blurrer text.
I wear glasses and 25" at 1440p has very clear text. I feel no strain. Even the grey text on HN is very readable from about 32" (81 cm) away which is my normal viewing distance. It's readable without much strain from 45" (114 cm) but I wouldn't want to use things that far away.
For reference my work issued laptop is a 13" 2020 MBP so I have experienced retina. I would take the 1440p screen real estate at ~120 PPI (24"/25") 10 out of 10 times vs going back to 1080p but with higher PPI. There's also the added benefit of never having to think or worry about poor UI scaling since not all apps handle scaling well, but that's not a deciding factor in my mind, more of a nice to have.
I believe that depends entirely on the desktop environment. Sway does real fractional scaling rather than the idiotic downscaling way.
Of course, independent of the desktop environment, you could just tell supporting applications to just manually render bigger UI (exactly how you would on X11 with some TOOLKIT_DPI variable thing per UI toolkit) and keep the monitor scale in the compositor at 1x. That's probably what you've been doing. That doesn't support multiple monitors with varying scale.
