What Charlie is saying here doesn't make sense...
http://semiaccurate.com/2013/04/29/nvidia-cancels-gk11x-line-rebrands-the-current-chips-as-new/
...that would make the GTX 770, apparently 25% faster then GTX 680, a faster card than the GTX 780 (Titan LE), which according to Charlie is less than 10% faster than a GTX 680...
Perhaps he meant to compare GTX 770 to the current GTX 670, and not the GTX 680. This would make more sense, since the GTX 770 looks like it will essentially be a GTX 680. Although, even 25% faster than a GTX 670 seems a bit of a
stretch IMO.
A GTX 780 based on a cut down Titan core would have to be seriously neutered for it to be less than 10% faster than a GTX 680. I also don't think anyone would buy it for more than the price of a GTX 680 if this turned out to be true.
Given that Titan is on average
47% faster then a GTX 680, I'd guesstimate that a Titan LE GTX 780 would be somewhere in the 25-30% faster range.