I agree too. I'm quite liking the models. The paint job is key. You have to go out of your way to make them look a little more aged. I also like spikey bits. The more the better. And I also agree, that the current studio CSMs are not painted with the tone that Chaos should be. They should look dirty, unmaintained and old.
But I also agree, that there should be more warped and mutated versions of CSMs, but in such away that they can be troops, not the elite possessed.