I'm currently in the process of recording my first large-scale piece using Klon. It's saving far more time than I thought possible AND it's giving me vocal effects that I would not otherwise have dreamt of. What would have been up to twenty meticulously recorded (and sworn over) vocal lines have been reduced to five, with Klon handling the 'beef-up' duties - and handling them magnificently. Used in conjuction with host automation, the flexibility is wonderful.
 
I have two instances of Klon, one for lead vox and one for backing (though there is no reason why the roles can not be reversed if, say, lead vox need an effect currently being used by the backing vox) and the fun is unbelievable.