Exactly what I am running with this 780 Ti, plus HBAO. Enough for more or less solid 60FPS with few dips. I could upgrade sure, but to play what? If there was a new Skyrim or ME4, I'd buy one as soon as its out here. Looks like I'll see what AMD cranks out.
If you're gaming at 4k or higher (multi-monitor) than anything less than a 980Ti/Titan X is going force you to make sacrifices if you're not interested in multi-card setups. If you're still stuck at 1080, then no, you don't need to upgrade a 780Ti.