Is a 4K tech mature enough to use it every day for desktop and software development? I've read, not so long ago, that Windows still have issues and plenty of apps looks just ugly. Also I read that there might be an issue to keep your old HD along with new 4K panel - some people experienced problems with such setup. Unfortunately, I've had no opportunity to test 4K so far. Also I have no idea how does it looks like with Linux systems.
I'm a software dev and use a 32" 4k monitor (3840x2160) at home. This is a 16:9 monitor (from BenQ). Unless you have 20/15 vision, you'll likely need to scale it. Windows 10 has built in scaling at 25% increments, and you can also do custom scaling. I scaled it to 115% and it works pretty well.
I also have a secondary monitor hooked up, but it's a 2560x1440 monitor turned vertically. It works fine, but I forget if font scaling is applied across the board or just to each monitor.
The ideal 4k desktop monitor size is likely at least 36-38", but I'm not sure if those are economical yet or not.
At work I have a Dell 34" Ultrawide (3440x1440). Not quite 4k, but no scaling is needed, and it's a great monitor. The one downside is that it's just got the vertical height of a 2560x1440 monitor, so I kind of miss the vertical height of my home monitor at times, but I can easily have three or four files side by side in my IDE.
I also have an Ubuntu system at home hooked up to the 4k monitor at home and it works, but you'll possibly need to adjust font sizing in your apps. I haven't spent a ton of time recently with this system though.
For all of these monitors you want a video card with Displayport 1.2. You do not want to use HDMI because you will likely end up at 30hz and that is a horrid experience. HDMI 2.0 supports higher refresh rates, but having both a HDMI 2.0 port and monitor is pretty rare.
Anyways, probably too much info, but it was either do this or work on an annoying bug :)
Just wanted to provide a counter point - I also have a 32" 4k display but find the default text size easy on the eyes without scaling. I do sit pretty close to the monitor though, about half an arms length away (elbow to fingertips).
I move my head around a lot more to focus on different parts of the screen. But I like that experience.
My vision isn't great - I'm near sighted with 20/200 vision. I can use the screen comfortably at the default scale with glasses, or with a small bump in text size without them.
I'm using OSX, with Atom & iTerm2 mostly. So that may have different font rendering than Windows.
I've used 4k for many years. On Linux it was easy; I didn't use any GUI programs other than Chrome, so it was just a matter of changing font sizes. (HiDPI didn't work for a long time in Chrome, but changing the page zoom worked fine. That is long-fixed, though.)
On Windows, things have gotten better. I have two monitors of different physical sizes, one is at 125% scaling and the other is at 225% scaling. Windows resize as you move them between the monitors. Some old apps look like garbage, but it's really an issue of Windows developers wanting their app to look "special" instead of using standard components. The apps most affected are mostly useless, like tools for changing the LED color on your motherboard. Everything important works fine; web browsers, Windows explorer, Photoshop and friends, etc.
On a 24" 4k monitor, fonts look just amazing. It is spectacular how nice the shapes are and how smooth everything is. On a 32" monitor, it's business as usual, really. Not enough pixels to feel different from 100dpi that we've had for decades.
I use a 4K Alienware laptop every day with two Full HD monitors attached to it through the official Alienware dock. I'm using Windows 10 and due to internal company policies, I'm not using the anniversary edition which supposedly brought better environment for multi high DPI monitors support.
I can say that it is pretty usable, but whenever moving windows between monitors you have to fully move them otherwise you will get weird results. Another caveat is that not all apps support 4k so I get really small icons in some applications such as greenshot.
I'm using a mid 2015 MacBook Pro with a 4K display for development, and it works pretty well. Expose hitches a bit sometimes, but that's the only trouble I've had.
YMMV if you're using it to display something other than a terminal or browser though, and I haven't tried using this display with Windows or Linux.
