Well, from the above discussion the majority seems to be against Khorne, so I think we'll leave them out for another season. Personally, I don't think they are much of a threat at low TV, but as has been mentioned there's less experience of them at high TV and all the frenzy, mutations and wide skills access could lead to some interesting builds.
I'd feel particularly bad/unfair if someone ran them for 4-5 months in this league and then we banned them for being too powerful at 2000TV (!), so for that reason I'm being a little cautious, but I'd like a bit more data on them in 2000-ish TV battles first :-). We will, of course, reconsider them each season as we find out more about them, but they really are a bit 'young' as a team for now I think.
Feel free to disagree with this though :-), and if you can push the consensus the other way, I won't object to them joining us, but the feeling seems to be against Khorne right now from our most experienced coaches.