But with scaling, are you not simply getting effectively a 16:9 2k but a bit crisper with 4k?
I have tried one of those old 30 inch Dells with 16:10 2560x1600, and it's amazing how much nicer it feels than having just 1440 vertical pixels. The aspect ratio is closer to sqrt(2). I guess that's the difference.
I don't have scaling and all application font sizes are stock. 31" is goldilocks for me, it is about having 2160 pixels good for programming, not smoothed out 'retina', but native pixels!
I have a failed product according to the marketplace - cinema 4096 x 2160 resolution @ 24Hz with extraordinary colour accuracy. Perfect for code, useless for gaming and 60+ Hz video.
I am not sure I would want a 27" 5K monitor, even if it did work properly (mine has an early DisplayPort interface, pre-dating useful standards). If you get a chance to look at a 34" 5K monitor then I reckon that could be what you are looking for. Any bigger and you have to crane your neck or push the monitor further away.
How would you feel about having 1692 vertical pixels instead?
Aspect ratio isn't what matters, it's vertical pixels and vertical inches. A 32 inch 16:9 screen is almost exactly the same height as a 30 inch 16:10 screen.
I have tried one of those old 30 inch Dells with 16:10 2560x1600, and it's amazing how much nicer it feels than having just 1440 vertical pixels. The aspect ratio is closer to sqrt(2). I guess that's the difference.