i dont see it as using c3 instead of vue, to me c3 looks like a great complement to vue, and of course the other way around, ive been trying the c3 demo extensively and ive almost convinced myself of picking it up as a complement to vue 4/4 pro. But i cant see myself using just c3 or for that case just vue4/4 pro, in my eyes whats appealing is to use em together since both series have completely different strenghts and weaknesses and both series are very user friendly and the price range is more then affordable aswell. but thats of course just my opinion :)