Vengeance, I've been reading claymore religiously at the beginning of every month since you first mentioned it in one of your posts over a year ago (In that same post you introduced me to Rave Master.. another favorite of mine) Claymore is incredible. Kishi and Kubo could take a few pointers from it. (Actually Kubo is hopeless, nvm).
Aside from Clare, there is no such thing as plot armor in Claymore. Anybody can die, anywhere, at any time, in any way. So ILL. Even Clare, the protagonist, still has a rough fucking path to follow. So even though she may "live" through many difficult situations, it's not like she does so while sippin' on Crystal. Take Riful for example. She was quite well developed and then killed off in an INSTANT.
I think that characters' individual skills (or particular yoma-based/yoki-enhanced ability...I know that not all of them actually require yoki) are fascinating. What I really want to know is why the Organization didn't use #10 to combat Teresa when she went rogue. I think it is because Teresa was probably believed to be too powerful. And her acute yoki-sensing ability probably would have immediately alerted her if #10 had tried to manipulate her.
Yagi (the author) has SOO many routes that he can explore. As you mentioned, the possibility that the island is merely a yoma testing ground and that there may be an entirely different race is AMAZING. My only concern for Claymore is that the powers eventually get way out of proportion. I love this series and CANNOT WAIT to see how it turns out.