There's nothing much wrong with the 27-inch 2560x1440 LED screen of the TBD, except that I can't forget that crisp Retina screen of my former MacBook Pro Retina 2012. Knowing that my 2013 Mac Pro (QC/D300) is good for driving screens with 4K resolution, I've recently bought a Dell 24-inch UP2414Q monitor capable of 3840x2160 resolution. This is with 187ppi quite a step up from the TBD's 108ppi. My "Rev A01" UP2414Q is supported by Apple support.apple.com/kb/HT6008?viewlocale=en_US&locale=en_US, with instructions on how to enable this display at 60Hz with MST. System Preferences/Display offers five scaled resolutions (just like on the MacBook Pro Retina), with scaled 1920x1080 listed as "Best for the display". Mmm, best in which sense, I wonder? Running the UP2414Q side-by-side with the old TBD, I found that the scaled 2560x1440 resolution gave the best result, with as much screen area as the TBD (relatively speaking). While the UP2414Q is 11% smaller than the TBD, this is more than made up in my view with the increased crispness of text. I spend a lot of time in my preferred ViM editor, so this is important to me. Moreover, my old eyes benefit from sitting 11% closer to the screen, at which distance the size difference with the TBD becomes moot anyway. System Information reports the resolution of the UP2414Q as 2560x1440 at 60Hz, even though About This Mac calls it 5120x2880... System Preferences/Display can calibrate the UP2414Q starting from maximum contrast set on the monitor menu. Since I liked the way I had calibrated my old TBD, I sought to calibrate the UP2414Q likewise, and I was able to accomplish this to a large extent but not quite. The reason is that this UP2414Q is really bright, which looks beautiful, but which also necessitates turning that brightness down at night so as not to get jetlagged. And here is the only slight annoyance: brightness cannot be adjusted via the keyboard out-of-the-box. It should not be too difficult to bind the appropriate driver functions to the respective keys, however, something that I'm familiar with in GNU/Linux. So, here's hoping that the OS~X developers attend to this issue soon. They have already solved in my Rev A01 version earlier reported problems with waking from sleep. The UP2414Q uses more power than the old TBD, since it must push some 125% more pixels---the display goes by default into power saving mode after some 10 minutes of non-use. It is also no Thunderbolt dock, but has three powered USB-3.0 ports, two of which are used in my case by an optional Dell AC511 Sound Bar and Logitech C920 Webcam. These peripherals do not shut off when the screen goes into power saving mode. Both these peripherals are recognized by OS~X, and the Logitech Webcam opens when starting FaceTime. There seems to be an echo problem between the Sound Bar and the Webcam (or so my brother said during a FaceTime session) even when one of these input/output sets is turned off in System Preferences/Sound. Finally, going from the 27-inch TBD to a "near-Retina" screen at 3840x2160 resolution necessitates stepping down to a screen with diagonal size 24-inch or smaller. The buzz about the UP2414Q's big brother UP3214Q, giving 3840x2160 resolution at 32-inch diagonal, is mainly about increased screen width at about the same 108ppi as the TBD. It wouldn't have given me that "near-Retina" experience that its little brother does. Have fun!