After posting I saw that new AMD drivers have been released. A very quick looks shows no code optimizations for ESO -- but honestly I only read the short patch notes not the full notes.
I run two AMD 290x's in Crossfire and frankly, I'm not seeing much difference, maybe a small amount, I seem to remember noticing a tiny FPS change in PVP when I disabled it.
I can understand the power you are looking for for other games, but ESO hardly needs that much power. If I run ESO on my 780 on High it looks great; and honestly it still does on Medium.