I had not heard of that one, but I'm glad to be wrong this time. It's nice to see another brand get in there. With a few exceptions, anything larger than phone size seemed to be using LG for the longest time, in spite of the existence of a couple other manufacturers in that space.
By retina, do you mean it's able to perfectly scale the UI compared to the older 27" displays? I think that's the main reason Apple tended to prefer 5K here. They always went with resolutions that replaced 1 pixel with 4 when going from old to new. If you're just worried about pixels per inch, have you viewed one up close? I'm skeptical that it would look much different outside of cases where UI elements aren't drawn optimally well.
I personally tend to regard calibration as nonsense on most models, because most models are not able to rely on any kind of internal adjustment. They just remap the output signals going to the monitor in a rather imprecise way by measuring what is emitted by the display.
