If I think of all my favorite anime songs, I actually don't think I'd like it very much if Hikki sang them. After all, she has a very disinctive style and so the wide variety of songs she covered would all end up sounding similar to each other, you know, lose their own originality... sorry, I'm probably being hard to follow. But also, her voice is not very strong, so she might not be able to hit the notes.