Best bet right now is to wait until the initial phase of this technology is worked out. Secondary effect will be that it's cheaper as well. The Dell 5k monitor looks good to me, but personally I'm waiting for a 30" variant with more resolution and a cheaper price. Still holding onto my 4yr old Dell 30" for now.
Compared to a 28" 4k that I have access to at work (LG, I think), I find I can comfortably use a lot more text on a 39" 30Hz 4k ~$350 Seiki (discussed at http://www.elitetrader.com/et/index.php?threads/4k-ultra-hd-trading.279744/ ) that is my main monitor, even with its blue-green-red subpixel order that it does not declare to the computer in its EDID information (but still accommodatable in software for most text rendering), terrible color balance (fixable by flashing the 55" firmware if you don't mind losing the ability of headphones to mute the internal speakers), and the screen blanking for a second once or twice a day. However, I can think of some some counter-arguments, even for people willing to tolerate the Seiki flaws. Maybe the Asus has better color balance or color gamut, or something like that that makes a functional difference for trading. Also, my mediocre vision is not completely corrected by my glasses; so, perhaps someone with more perfect vision might not care as much about physical size of the display. Perhaps someone attempting to trade using realtime charts would find more value in the sharpness of detail, even on a small display, that might better distinguish between frequent small fluctuations and inactivity. I don't have experience trading that way. My use of computers for trading is primarily to consider strategies that usually involve holding for days, basically just ordinary software development with numerous windows for text editors, debuggers, data, message logs, and documentation. Finally, looking toward future prices drops, it's not unreasonable to plan to allow physical space for multiple 4k displays. Regarding the discussion about curve, the idea seemed like a gimmick to me until I started using a 39" display regularly. Now I find myself wishing for a curved display perhaps daily, when I lean or move my seat to look closely at a window located at the edge of the display, or drag a window closer to where I am sitting. On the other hand, when I use the entire display to watch a movie (I have the same display at home), I tend sit a bit farther away, so I don't find myself wishing for a curved display for that.
I just bought a dell 27" 4K monitor. I will say the chart is too small for most people. 32" maybe good.