There are cases where NV's cards just run faster too though. Like BlackOps where a GTX275 is a solid
57% faster than a 4890. Generally speaking though, I agree with you that AMD's cards tend to "age" better with time. This has been true for several generations actually (outside of 2900XT and 3870).
For insance,
X1900XT 256mb gives a 7900GTX 512mb a beating and a half in Call of Duty Modern Warfare 1. Back in the days a 7900GTX was not that much slower.
In LP2 though, DX11 brings in extreme tessellation. This is probably why NV's cards outperform AMD's under that setting. Ironically, it hardly improves the visuals.
We have seen what code optimization for a specific hardware can do on consoles. It's very possible that AMD worked very closely with Bioware to optimize the code specifically for their highly parallel architecture. It's a fair game.
NV pays $ to developers to crank Tessellation to "64 billion depth". Wait until Crysis 2 DX11 patch. :awe: AMD's cards may run faster with some of these effects: SSAO, bloom, depth of field. (see HD6990s slide to see the specific features). It's just exploiting your architecture's strengths. We won't know for sure until NV has had a fair chance to improve their drivers. I was always under the impression that NV had a superior DX11 architecture but DA2 makes me question that opinion.
I haven't seen Shogun 2 DX11 benches. Do you have a link?