Yeah.. you got.. the 7990 has come down a lot because of hawaii.. lol. I would still take sli over crossfire.. but if its single GPU, then I would take which ever is more powerful. I would take a titan over a 7990 or 690 any day on an unlimited budget.
No need to apologize :S $579.99 with rebate! Cheapest 780 on PCPartPicker: 635$ -- Difference of 55$.
I know just looking at one page to determine which card to get is bad, but here is why the 55$ is worth keeping over a 780. (That's why I say, only if you know for a fact you will hate the microstuttering [they don't call it micro for no reason], you should go with a 7990 or 2x7970.)
Just wanted to say that the Galaxy 780 HOFdoes not need a 600W PSU, that's ridiculous.