I'm thinking of replacing my 27" 2560x1440 monitor with a 32" 3840 x 2160 monitor.
How is the FCPX interface on those? Some people seem to think that macOS' UI gets a bit too small on those? Anyone using that setup? (I will have only this monitor)
It's not the OS or the app, it's the graphics card you have driving that monitor.
You can adjust how large or small the GUI is on any monitor in the System Preferences, that's a non-issue.
But 32" is a HUGE monitor.
I use FCPX with a 32" Viewsonic VP3268-4K at full 4K resolution and sometimes not even at full screen height/width. No problems at all. I'm 59 and need glasses to see my monitor sharply, otherwise without them it's a little bit blurry but still readable. I've not had to scale the OS down for FCPX - unlike some of the digital audio workstations (DAWs) I use to create and sequence music. If you've ever seen Reason 10 (or the new 11) you'd know that this software is unusable on a 4K monitor without scaling - so you lose the advantage of more screen space. But FCPX is not a problem unless you have a relatively serious visual disability that can't be corrected satisfactorily. The Viewsonic has stellar specifications although the price point is middling in the 4K range. Not sure if the attached pic is helpful but have a look.