yes, currently ive just upgraded my system to a maximus VI hero, 4770k, 32GB of corsair vengeance, and still use the GTS250 from my previous PC.
so i can SLI and have no problem doing it (love the EVGA bridges) and was just interested wether its wiser to wait so i get funds since if i buy the 760 now ill only be able to get another around march and i can get one 770 by christmas.
so how much of a difference does it make, playing at 1600p?
oh forgot to mention, ill be playing metro and bf4, as well as do lots of 3d rendering and such.