White blood felt out of place to me. I mean, stylistically it looks... cool I guess, but the way it was explained and thrown into MGS4 felt awkward. It doesn't help that mysteriously the white blood is in the Japanese version of this game (I think it is anyway?) Not sure why they're different, really. I would have been okay with an option to switch between red and white blood but I suppose it wasn't possible because of the way the cutscenes were done.