I'm not currently playing competitive FPS or something like that...
A better quality image ( and low color shift ) could be a great improvement in many other games
And BTW high refresh rate gets more useful in competitive multiplayer games if you already have a good connection, and italian "broadband" sucks
p.s.: driving a 4K monitor over 60 FPS is going to be quite difficult with a single card at least until the end of 2015, maybe 2016
I suppose it depends a lot on the type of games you play. I pretty much play MP games exclusively, mainly competitive and not the slow type. Also racing games, which benefit a lot from 144hz. I'd probably prefer IPS for RPG games as well, even though even in those games high refresh rate adds a lot to the experience.