@Da Best Ever, obviously Nagato has more power than Itachi. But while Itachi was in Akatsuki, he was sick and becoming blind at some point. He was better off spying than killing the other members. If he were to fight Nagato, even if he were to win by some luck (Nagato had alot of power but was seriously nerfed. At best, since Itachi knew his secret, he would have to somehow distract the 6 paths and just go after Nagato himself. Nagato was crippled and totally drained by using the rinnegan, that's why he relied on the paths to fight for him. If Itachi did that, I guess he could easily kill Nagato who himself is in no condition to fight either), it would take alot out of his eyes. Itachi was fighting to live just long enough to fight Sasuke and transplant some powers to him. I don't think he would risk wasting his MS on an attempt to kill Nagato. Especially when that would blow his cover and the other Akatsuki members would gang up on him as well. He wouldn't be able to kill all of them if they were to all go against him (and they probably would all go against him at the same time, they would just call others for help). I do realize that Kakazu got away w/ killing his partners, but the case is different for Itachi. Kakazu was known to be hot-headed. Itachi was not. He was calm and level-headed. The other members would think something was up if he randomly started killing people off in the organization. Especially considering that he was a part of Konoha's Anbu. They would probably piece it all together if he attempted to kill other members, it's not that easy.
