If you're going to play Sisters you need the CA. Trying to play Sisters without CA is like trying to play Dark Eldar without the codex.
RedTwo,
Exactly my thoughts! In any game, whether role-playing or war-gaming, I always stay away from humans, especially if they're from a society I view as immoral and fascist *cou-Imperium-gh*. Our fellow humans can be so exasperating at times! (To put it rather lightly.)
As for the "Amazon effect", do you think it has something to do with evolution and the whole Darwinism thing? Just a thought.
'Nids! I play 'nids too, so I'm inclined to say "Good choice!", but I, um, well... ah, what the heck. Good choice! I like 'em because they're wierd, they're ugly in a cool way, and they get all manner of wonderful biomorphs and such. In fact, I'm writing a supplement to the codex. It's still being tweaked, but I have much of it done already.