Yes, the UI is tiny and too small (for me) on a 27" display. The font size for the pattern editor can be increased, but that's it. I imagine if you sit very close to the screen, it won't be too bad, but I sit 70+ cm away from the screen. If I increase Windows 10 scaling to 110% or 125%, Renoise looks blurry. Either way, the experience causes eye strain and fatigue for me.
I looked into getting a 32" 1440p display, but there is really only one option with the other requirements I have (non-curved, G-Sync, 144hz+) and the reviews for that model didn't convince me, and besides, I don't want to spend €700 on a monitor that I don't really need (I have a display with all of these specs, just in 27"). A 4k display isn't an option for me right now because there are no models with 144hz or better and G-Sync (and my 980ti wouldn't cut it for 4k gaming).
OK, I think I already have a rough idea. I'm seriously looking at a screen that is 32-35" high by 1440. I guess 32" with 1440px the size will look like a 24 "1080 px screen, I'm not interested in the 4K, they're too much faces and graphics cards too, I think the best current format is 35 "2K widescreen, which has the resolution small enough for the graphics card to perform well without leaving you a month's salary.
I also think that 27 "with the resolution 2K is a lot of resolution, that is, it will look smaller in this configuration than in a monitor of 24" to 1080. The best thing would be to compare 2 monitors side by side, but unfortunately I can not. Choosing a large monitor is one of the most expensive components of the PC. Also the most complicated to choose.
Another issue that concerns me is the response time, or the frequency, to be able to use dark themes and that the parameters in the pattern editor are not "blurred" when scrolling. I do not know if you have had this problem. It seems that the color change of the LEDs is very important to see the information in movement, especially with dark subjects, with black background.
I could create a forum just to do a small study of the best monitors in this range of sizes 32-35 ", to see what would be the best option without spending too much ... Spending more than € 400 on a monitor seems already too much to me. the € 500 would be reasonable if the monitor really convinces me.