Just a quick note: The affordable, and color accurate 24″ 4K display from Dell (UP2414Q) does work on recent Macs. Even my not so recent mid-2012 Retina MacBook Pro. However, on these, and even the later Retina MacBook Pro it only runs the full 4k resolution at 30 Hz. On the newer it should work with 60Hz, but this currently looks to be a Mac driver limitation.
Switching to HiDPI mode requires some hackery, as Mac does neither do this automatically according to the DPI that could be derived from the DDC EDID data, nor does it offer a UI option to do so, … :-/
As I never in life run a display at 30Hz the first thing to notice is mouse lag. One would think it would be snappy, given that regular cinema runs at 24Hz. But at 30Hz mouse input just feels laggy and decreases the feel of using the UI with the mouse quite a bit.
Of course working with graphic, text, most notably source code at HiDPI is just amazing. What Apple should fix:
- default to HiDPI with a scaling option for external display, just like for internal
- fix the driver of latest Macs to support high-bandwidth, Multi-Stream Tiled displays
PS: 16:9 really is annoying for work, 16:10 should be the standard for Pro work, and cinema is more like 21:9 anyway, …