Your kid is definitely in a different league than mine...BUT...I still think you might want to try to keep her in children's books for a while longer. The older British ones can be very sophisticated with language, and even despite her intelligence AND apparent old-soul stuff, there is a lot with adult books that isn't going to be right. PLus the canon of children's lit contains so much goodness--and IMO, is important to cultural literacy. There's plenty that really isn't worth her time, and there are adult books she could add in, of course. But I'd really try to not let her think that she should be leaving kid lit behind.