If you take a good look at the "Lag" section of the TFT Central review, you'll see that the 2414H has an awesome reaction time!
http://www.tftcentral.co.uk/images/dell_u2414h/lag2.jpgOfficial Data Manufactures write in their spec sheet cannot B's trusted!
The Problem with Monitors is that most people just have one type/model of monitor and keep that for a few years. So comparisons between different monitors are difficult for normal users. Therefore most advice you'll get will be ft review sites.
For the question of switching from 5760x1080 to 1920x1080, if you're not in game that's a simple key press, windows +P and you can toggle the mode in 3 seconds.
As for performance, I'd recommend a 780 SLI over a 780Ti, price/performance point of view.
TriSLI is a bad idea! When you get +90-100% performance from 1 to 2 cards you get around +8-20% performance plus from 2-3 cards and not the expected +50%.
Crappy drivers FTL