The problem with the movie is that while all these theories make a lot of sense, none of them were thought of or utilised by the writers. I saw it again tonight and was able to sit back and observe a lot more, as I wasn't hanging on every bit of dialogue.
They're really explicit about Khan's blood being Kirk's ONLY chance. And there's absolutely no hint of an explanation for not using one of the other augments. They could've quite easily said that the bodies would take too long to defrost, as the cryotube wouldn't be able to sustain Kirk's brain signals for long (it was after all designed to sustain a living body, not a recently deceased one). But they didn't bother with anything like that. They just assumed we wouldn't notice.
Also, on a second viewing, I'm convinced Cumberbatch actually styled some of his performance on Ricardo Montalban's. There are a few places where I think this is evident, but in one part in particular where he's talking to Spock on the viewscreen (mirroring the "Genesis? What's that?" exchange) the similarity of his posture and facial expressions is so similar it must be deliberate. Which is admirable of him, I suppose, but just makes it all the more weird that nothing else about the character's personality or abilities is carried over.