On an aesthetic level I would say the Acer is more of an adult's monitor. Not sure why the ASUS one has all the extra detailing on the back. Was the opposite with the 2560x1440 the ASUS looked like you could put it in an office and the Acer looked like it was made for a 14 year old.
Can 780Ti SLI push 3440x1440 at 100hz? Non sure on that one. They are roughly a GTX980 in performance if I recall, and I don't think a pair of them would manage too well, they didn't always perform for me at 2560x1440 in all titles. Depends on the settings I suppose.
2560x1080 is going to be a pretty low pixel density at 35", basically a 27" 16:9 stretched out. I like my old 27" 1080p when I bought it, it was huge and 2560x1440@60hz was still super expensive. But it wasn't the best thing to read on.
But if you are willing to spend 1200 on a monitor, maybe a GTX1080 or two wouldn't be outside your budget.