Could you explain? We have three different 4K 27" screens around the house and for me the five options between Larger text and More space in Display Preferences are completely fine? I pick the size I want and the fonts are completely crisp? If you want to select resolutions, you can hold the Option key and click the Scaled radio button and you can select concrete resolutions.
May experience with Linux has been the opposite. Integer scaling works well (assuming that the toolkit of an application supports it), but once you use fractional scaling (even on GNOME on Wayland), a lot of CPU cycles are burnt for rendering, and many non-GNOME applications will be rendered at a lower DPI and scaled up and everything is blurry. I had a ThinkPad with a 1080p 14" screen and an external 4k 27" screen. Both were practically unusable. With the native resolution everything is too small, with 2x scaling everything is too big, and with 1.5-1.75 scaling, many applications are blurry. I ended up using the native resolution and scaling up the font size. At least text was not too small or to big, but a lot of widgets were tiny and barely usable.
In Windows the options themselves are fine, but there are too many legacy apps that do not support scaling and just look blurry :(. And with plugging/unplugging of an external screen, Windows was often not able to put windows back in the right places.
HiDPI scaling was one of the long list of issues that made be go back to macOS after using a ThinkPad with Windows and Linux for 7 months a year ago.
On my M1 Mac though, I need to pay $50 for eqMac2 so that I get to control the external display's speakers. Then I'll need to pay for Switchresx or Better Dummy just to get the resolution right on my non-4K display. And if money is not an issue, the security of these apps is definitely concerning. It all feels "hacky" to install app after app just to get the standard functionalities on macOS.
The fact that Apple removed HiDPI for non-4K displays just shows how non-free the whole ecosystem is. Definitely one more reason to wait for Asahi Linux on M1 Mac.
Like I said, all my 4K 27” screens show crispy text on macOS.
I'm currently using 2x 27 inch 4k displays in scaled mode (the second setting from the left) on an M1 mac and it looks great. Fonts look fine to me.
It’s not 2X integer scaling but I don’t notice at all.
This probably means it was trying to do subpixel rendering, but under incorrect assumptions about what the subpixel layout was. Problems of this type have recently become pretty pervasive.