its a tough call, if i had the budget id get a titan x with plans for another come cv, but at $999 thats insane...
that being said I just spent 600$ on a gtx 980 in hopes that i can get another one for cheap when CV.
hopes hopes hopes its powerful enough.
in terms of performance,
the stock clock speed on the titan x is less than or the same as the 980 (depending on which one), but the titan x has 3000 cuda cores vs the 980s 2048.
Im not sold on the price/performance of the titan X.
id say wait as long as possible for prices to come down and they already confirmed the gtx 980 ti, which will basically take down the titan X with power, but vram will only be 6gb vs 12gb (which is plenty!)