Your review is the only professional review on the Internet where GTX660Ti beat HD7970 in this game with Beta 12.11 drivers. Everywhere else, HD7970 is at least as fast or faster than GTX680:
Guru 3D: HD7970 > GTX680
http://www.guru3d.com/articles_pages/medal_of_honor_warfighter_graphics_vga_performance_review,1.html
Techspot: HD7970 > GTX680
http://www.techspot.com/review/591-medal-of-honor-warfighter-benchmarks/page5.html
GameGPU: HD7970 = GTX680
http://gamegpu.ru/action-/-fps-/-tps/medal-of-honor-warfighter-test-gpu.html
Tom's Hardware: HD7970 = GTX680
http://www.tomshardware.com/reviews/medal-of-honor-warfighter-performance-benchmark,3336-6.html
How in the world is a GTX660Ti faster than HD7970 in your testing? Also, why do you have GTX680 paired with 2600K but HD7970 paired with i5-2400? I don't understand your testing methodology. Finally, you are missing HD7970 Ghz edition which is the flagship HD7970 series, not HD7970.