Nightwish and...oh, I don't know, Leaves' Eyes, let's say.
I actually think Liv might be quite good at the older Nightwish songs, since she has great range, but the newer ones with Anette...it'd be like Tarja trying to sing Amaranth, and that scares me a little. :P
Anette in Leaves' Eyes may not be so bad either, I mean some of the songs may be a little more difficult since it's not her style, but she's pulled it off quite well with the old NW songs, so I see no reason why it wouldn't be okay. Not as good as Liv, but then Liv Kristine IS Leaves' Eyes, pretty much. :)
Edit: The interesting thing is, the Anette-haters actually compared Anette to Sharon a lot, but I don't see the similarity at all. :D
Here comes the thumbs-down...can't wait.