No matter which way you look at it, the 28nm Die has about reached it's limit. I don't care whether it's Red or Green if you pay $150 over $549US/$599CDN for another measly 5 to 8% for performance at the expense of heat and noise, that's up to you.
The 20nm die may be better but who's to say when you consider Intel's SB Vs IB CPU's in regards to Performance over Heat and sufficient Cooling.
These last Perf/Price offerings of the 28nm GPU Die just may be the Best of what we are to expect for a very long time or at least till we have to upgrade the whole Platform which will not be anytime soon for me.
-----------------------------------------
i7 2700k/ASUS P8Z68-V Pro Gen3/Corsair H110 AIO (running @ .996v/1600Mhz to 1.376v/4600Mhz 24/7 between 36 to 67C), 4 x's 4GB sticks of Samsung MV-3V4G3D-US DDR3 running at 1.34v/1866Mhz 9-9-9-24 1T with 4GB's assigned to a RAMDisk drive to handle Win7 sluff and negate writes to the SSD, Samsung 840 Pro 256 SSD, 2 x's WD5001AALS HDD's in Raid-0, 1 x's WD1002FAEX 1TB, ASUS DRW-24B1ST DVDRW, Hauppauge WinTV HVR-1250 PCIe, XFX 850W Pro Black Black Edition modular PSU, EVGA e-GeForce GTX 280, Fractal Design ARC Midi R2 case, QX2510 Samsung PLS 2560x1400 res display at 120Hz.
Up Grading GPU pending price of AMD's Radeon R9 290X offering Vs nVidia GeForce EVGA GTX 780 Classic or 780Ti.
I'm ready for 1440p 4K PPL gaming and that 512 Bit/4GB Hynix vRam AMD R9 290X looks very nice to me perhaps the cheaper R9 290 ;o)