i wouldn't put much stock in the accuracy of that spec sheet graphic someone made up. i know for a fact that the 34UM67 listed specs are wrong. it's a 3440 x 1440 resolution, 60 Hz IPS (more like VA) screen.
most modern games support Hor+ which is the ideal solution to wide screen/ultra wide screen resolutions. you can go here http://www.wsgf.org/mgl?title_op=starts&game_name=0 for a compilation of games that support different wide screen resolutions.
the problem is that most of these displays will have to be physically opened up to reprogram the display controller, which is why you see Iiyama offering to do free recall's on 4k monitors they're selling now. most people just don't have the ability to do this themselves. it's not like...
saw this http://www.tomshardware.com/news/lg-34um67-34uc97-34uc87m-ces,28287.html yesterday. looks like the only current 21:9 LG with FreeSync supported is the 34UM67.