Our bodies aren't set up to live on grain alone. Soy protien has shown to have a number of issues the body is far less prepared to cope with than the problems associated with meat.
Let's not forget that in order to crank out the yield of grains you quoted, a farmer has to use GM grains, something I'd bet my heavy sixer on that you're against.
But it's not 'karmically correct' to eat animals, right? Sheesh... Look, if you want to be 'humane' about it, vegetables have a nervous system as well. They feel something when damaged, that much is known, and I doubt it's an orgasm. So all you get is fruit. Or would you needlessly slaughter the infants of an entire species as they writhe in pain in front of their mothers? Monster.
I'm not of the religious 'we're above them' mentality; I'm of the Darwinian 'we're above them' mentality. On this one, even The Shawn and I can find common ground.
Watch a cat play with a mouse. That's what happens to food, it's seldom pretty or humane. And if you want to say 'we're better than them', I agree. So much better, we are the king's and they our foodstuffs.