I've had 2 680's in SLI for a little more than a year now and I am yet to run into a game that has issues because of it; all I've gotten is insanely awesome performance..
I have to say my piece about the triple monitors however...
Have you considered just getting a single, large, high resolution display and instead playing games at 1440p / 1600p?
I have had quite a bit of experience with both and, in my opinion, having one really nice display is much better than having 3 displays.
If you get a chance, you should really check it out. This is a good time to buy since the prices have dropped significantly because of 4k.
Just something to think about it.
Hope this helps.