LOL. Everything where AMD isn't ahead is "biased" to some... Your own chart shows Metro:LL running +15% faster. Given there are differences of
+23% in Crysis 3,
+38% in BF4,
+32% in AC:Syndicate,
+22% Overwatch,
+27% Tomb Raider DX11,
+21% Mirror's Edge Catalyst, etc, and many other mainstream DX11 titles vs the RX480 at 1080p, that's hardly worst case. Real cherry picking would be something like
Anno 2205 (the same +30% outlier as your own inverted "correct" selection of DX12-only titles).
4GB vs 8GB RX 480 has been measured to be a mere 3-5w (and that's with the larger quantity clocked at higher speeds):-
http://www.anandtech.com/show/10446/the-amd-radeon-rx-480-preview/6
^ And that's why when measurements that turn out half to a third as much as "
it WOULD perform..." forum guesstimates, the only real answer is "show me" (preferably in a wide spread of +30 games that aren't equally obviously cherry-picked for DX12-only AMD bias, and are measured "like for like", ie, you undervolt both or neither...)