Hm, I'm gonna need some convincing here. Danzo with his Sharingan brings him better reflexes. I can't see Danzo falling for the same trick six times and without Tobirama having his strongest jutsu of the exploding tags, I don't see Tobirama pulling off the win more times than Danzo. Danzo is smart and experiened and is fighting his old sensei. He can deduce the secrets of Tobirama after a few deaths as Danzo does well with his offense as well. Regardless of Tobirama's speed, Danzo and his Sharingan can keep Tobirama on the defense. Then again, it seems like Tobirama is stronger than Danzo, I just have that feeling.