I am going to echo the comments that this card is what the 680 should have been, and nVidia may have shot themselves in the foot with the 680 and the changes that made the 680's DP compute performance less than that of the 580 as we see once again from the results in this article.
I really think that what nVidia was trying to do is push DP compute to the pro market, and thus the exorbitant prices for the Kepler based Teslas. My guess is that the Kepler Teslas did not fly off the shelves as nVidia hoped. If this is the case, Titan may not be a bad Kepler Tesla, and it could actually be the same chip that is used in the high-end Kepler Teslas except that it has some functionality deliberately turned off in an effort to salvage chip sales that otherwise are sitting on the shelf. The problem being that in order not to offend those who spent megabucks on Kepler Teslas, Titan was priced astronomically.
Now along comes the 780 with functionality slightly less than that of Titan, and it makes me wonder even more whether nVidia is just killing of parts of the Kepler Tesla chips in order to salvage chip sales.
This is just speculation, of course, however, it is not outside the realm of possibility as I see it. nVidia most likely would never admit that they are killing functionality on good parts in order to salvage chip sales and not offend those who have bought the high-end Tesla cards. Doing so would be customer relations suicide.
When I bought a new 580 a year ago at $399, it was a value buy for my needs (DP compute performance, among other things, was important to me) in comparison to what I would have paid for a 680.
I really do think that nVidia overestimated what the market would bear with the 680 and Kepler Teslas, and the Titan and the 780 are attempts to find the market again. Perhaps in a year or two, nVidia will regain its sanity. Until then, I'll pass on these cards unless I can find one in the used market in a year or two at a reasonable price.