Hey, So I've been debating this back and forth for myself for one week now, and am guessing that maybe some of you guys are in the same spot with your Mac Pro. So I wanted to share the experience that I made. I'm writing this for everyone who feels like I felt - uninformed about 4k @1440p @27", because there's no way to check it out. I always thought that it's complete nonsense to have 4k at this screen size. But I was wrong as it turns out. I've had two ATDs since the original Mac Pro purchase in Jan 2014. I LOVED these displays, even though they were already too thick back in the day, compared to the imac I owned before the mac pro. Still, very stylish displays. I was happy for three years with them, but recently purchased a macbook with retina display. My Eyes started to hurt when I was looking at the 27"s from that day on. I started to look for alternatives. Originally I wanted the Dell 2715p 5k Display. Of course, you need 5k to get the true retina experience on this screen size, not silly 4k. But it turns out - Dell and HP have both discontinued their 5k displays! They were unable in the entire German Internet! Huge bummer. Then again I thought, maybe they were just not ideal solutions with their Dual Display port connectors. The new LG Display won't look good at the Mac Pro with the upscaling taking place. SO I turned to Dells 2715Q 4K display. Got it today. I was SUPER sceptical about how the 1440p scaling would look like. Turns out for no reason really. It looks 10 times better than the Thunderbolt Display, I can promise you that. Pictures following. I realize it's not as good as 5k would be obviously (also did one test where I scaled it to 1080p wich is how 1440p would look like on a 5k display regarding to crispness). But since there's as of this moment NO solution for Mac Pro users to get 5k working, this seems to be the only way to get somewhat of a retina solution, until the MP gets an update hopefully later this year. I sold my two TB displays for 600 € each, just as much as the Dells cost me, so it didnt hurt at all. It's a huge upgrade in IQ, even though I hate the look of the display, especially that it's not edge to edge glas, but has this silly Border, and no webcam/mic of course, which is very annoying. The matte surface is actually bearable. It even has some glossiness to it. What's great overall is how perfect the display works in conjunction with Sierra and the nMP. No sleep/Wake issues or anything so far. But anyways, I'm certain later this year, true greatness will await, and then I'll just swap everything out and have had a few months with a super sharp display anyways. No regrets. All you see is scaled 1440p, except the one image that states otherwise!