Hm. So bottom line of what I have learned so far:
4K is out b/c it's not useful @ 27-30" screens and software scaling is more trouble than it's worth.
Freesync is worthless to me because it doesn't work with windowed gaming. (I play mainly in windowed because it's so much more comfortable to switch in and out, esp in games like WoW or FF-XIV)
GSync works with windows but is ridiculously expensive and on top of that, there seem to be only 4-5 monitors available at all in the 27" / 1440p range, most of them some rather ugly (dat red Acer Predator) "gaming" devices. While certainly nice, I'm not sure a 200€+ tax is justified because if I am honest: I'm not the hardcore gamer anymore that I used to be.
IPS may have a glow effect that could bother me in dim/dark rooms esp during dark scenes. (no way to be sure but to order one and actually try it out)
On top of that, there seem to be serious issues in terms of QC in Asus/Acers/Dell camp. Lots of bad experiences scattered over the Internet.
So what remains would be: IPS vs VA (really want to get rid of TN color shift) and 120+Hz vs 60Hz.
If I look at IPS & 120Hz+, there only seem to be a handful of monitors out there either and guess what: they seem to be the expensive g-sync ones.
Just for kicks though: I took a pic with my trusty Canon SX130 IS of my current monitor (BenQ G2222HDL) with an all black image. Granted it's not night-time right now but I can get my room pretty dark.
I used the following settings: 2.5s exposure, ISO 200, F4.5 (I think aperture width or sth?) and manual focus of 50cm.
Even with these moderate settings, my cam perceives that as far more critical than my actual eyes.
As for the colors:
I used the following settings: 0.3s exposure, ISO 80, F6.3 (I think aperture width or sth?) and manual focus of 50cm. (Impossible to recreate exactly, this was as close as I could get)
"Original image":
For the record: my monitor runs in the "eco" setting @30% brightness b/c my eyes are quite sensitive to light.
What do you think?