First of all, as you get to the higher end cards, the gap between performance gets smaller and smaller. When we go to 20nm expect to see some interesting changes.The GTX780 has been out for 6 months, yet the R9 290X is only 10% to 15% more powerful in frame rate benchmarking over a stock GTX780? Really? That's all? This is to be expected and is definitely NOT worth the extra $100 to buy a R9 290X over a GTX780. What isn't shown here is that the frame latencies are still superior on the 6-month old GTX780 - nuff said! I would rather have lower FPS and a smoother gaming experience than higher FPS and a bunch of choppiness. NVidia FTW!!
The real question now is how many game developers will be fully using the Mantle API.