In my opinion, Darth Tyrannus should not have used Sith Lightning. Yes, his lightning is a crackle compared to the veritable storm Sidious conjures up, but it still infringes on the power and uniqueness of the Sith Master, Darth Sidious. Making Sidious be the only one who used Sith Lightning makes him appear even more powerful, which is a good thing IMO. Another thing: When Yoda absorbs or deflects lightning it appears to be really hard for him to do. But Dooku was able to deflect it with his palm very easily and without any effort. Furthermore, his hands did not glow like Yoda's did when he did so. Why is that? Because he was using the Dark Side to deflect it?