The U3415W is the monitor I finally got at work. It's a nice monitor.

At home I have a Benq bl3201pt, which is a 4k 16:9 monitor. It's nice as well, but does have a flickering issue (one side of the screen will flash every 4-8 hours or even 1-2 days).

I use an X34 at home, aside from quality issues (needed a warantee repair after 6 weeks, nontrivial shipping and hassle), it's a fantastic monitor for every task.

I've never understood the tendency towards multiple monitors over one larger monitor.

I find multiple monitors easier to manage with a tiling window manager and offer a better "separation of concerns" in terms of grouping of active applications I want to see. But my home set up includes 3 28in displays so I may just have a problem, ymmv.

Nice. Mine could only do 95hz after a while on 100, started flickering; other than that no issue.

I surround my home X34 with two U2412Ms on an Ergotech stand.

It's a pretty neat setup.

Its easier to independently change the workspace running on a secondary monitor than it is to rearrange individual applications.

Why a 1440 vertical pixel monitor?

Real 4K monitors are effectively the same price and have a lot more pixels. And you can get them in 27", 32" and 34" sizes.

Sure, I understand why the manufacturers want these odd kinds of resolutions so that they can take defective panels and carve them up differently.

However, why would the users want these instead of more resolution? What am I missing?

1440 vertical pixels in a 34" 21:9 monitor means you usually don't have to worry about whether your software can adapt to a non-standard DPI. At about 109 DPI, it's the same as a typical 27" 16:9 panel, just with more pixels off to the side. The density is a bit higher than the typical ~94 DPI of a 24" 16:10 display, but the difference can be tolerated by most users. Jumping up to 140 DPI (32" 4k 16:9) is enough that you either need exceptionally good vision, or you need to compensate through software scaling adjustments or major ergonomic changes.

27" iMac has been 2560×1440 from 2009 until they went retina in 2014 (and they're now double in both dimensions, so same logical resolution).

At arm's length, on a 27" screen, 1440p is very practical. Getting more screen space than 1080p is what bumped me from 21-24" screens, and it fills my vision enough that if I jumped to 4k I'd either be moving my head back and forth with a 40" screen, dealing with even smaller UI elements, or wrestling with OS scaling.

How about a 42inch 4K monitor (Philips BDM4350UC). In term of screen real estate it is fantastic.

In terms of PPI, not so great.

For development I take screen real estate over PPI. The idea is to run it at native resolution while being very readable, and to be able to work on multiple documents side by side.

(And for coding you actually need height more than width, if you think of a typical layout of a code file)

To each their own. I love the fact that I can't see pixels on my retina iMac at 220 PPI. It makes reading code much nicer.

I still have more than enough room for a few buffers on screen.

I agree with you. I'd love to try a 4k screen, and was even considering it - however in the end I took my home U3415W to work and bought the X34 for home (I might game 30 minutes a week or something; the extra hz are certainly nice for that, otherwise they are pretty much identical).

I value actual real estate over PPI, preferring to run at 100% / unscaled which looks much nicer in Win10. The 109PPI (3440x1440) is decent enough, and I don't have to squint. Furthermore the DPI matches those of the surrounding 16:10 24s (1920x1200) well enough for it not to be an issue.

I am trying not to cargo cult here but I think if I need to scroll a file with 9 font on a 32"+ screen with 4k display it might be a sign of code smell (again, this should definitely not be a hard rule just saying it might be nice to stop and think why it is so long)?

Not arguing against that, however Visual Studio has lots of windows eg NCrunch runner, output, solution overview in addition to editor(s).

The ultrawide allows for this nicely; tests on the left, two actual editors, solution explorer on right, and output at the bottom under the editors.

Do you mean 9pt or 9px font? Either way, that's not comfortably readable on a 32" 4k screen.

On a 34" 3440x1440 screen I keep IntelliJ at 14px (10.5pt). On a 32" 4k screen I keep it at 15px-16px (~11pt).

You're still only talking ~100 lines of code on the screen at any one time. Maybe ~130 with a smaller font.

It doesn't appear to be curved or ultra wide screen.

It's not curve but you can see it as an ultra wide screen which is also very high.