Ignoring the recent hotfix. Is there any reason to be Obliterating as Blood?
An incredibly well geared Blood Tank told me he does it for aggro. Now maybe he has frost sub-spec for Annihilation, though I'm not sure whether thats reccomended. But as far as I knew. With DS glyphed and specced. It not only deals more, but heals and puts a shield up. That alone should generate heaps more aggro.
Am I missing something?