Ddrnai already widely used in plants, it works takes 5 copies per cell not worried, big pharma and skiddish investors, litigation, frankly theft by companies like gradalis, you got American elite ism, and one other thing I don't think benitec is using bi functional Shrna which takes on the full advantages of Sirna. yoo read this paper folks
And really look at the pictures http://www.sciencedirect.com/science/article/pii/S0169409X09000969