actually he would lose the advantage in either Scenario. he can use White Rage but Mu and Tobirama are bad match up for him, actually they have better chance to win than itachi and sasuke, they are both sensors, , Mu dodged KCM Naruto, and Gaara's Sand Twice, he displayed the ability to sense chakra over a distance of several kilometres, as well as to discern the similarity between of chakra signatures belonging to close relatives such as Gaara and his father, and distinguish chakra fromdifferent populations. Furthermore, Doton: Keijūgan no Jutsu would help him alot to evade most of Kabuto's Chakra scalpel attacks, By simply touching the ground with his finger, Tobirama could detect the presence and number of enemy shinobi, He was even able to detect Madara Uchiha's chakra on a battlefield far away, despite being in a different country. Tobirama would tag Mu to evade most of Kabuto's offensive Jutsu, Manda 2 gets annihilated by Jinton, Mu senses Muki Tensei and Evade it with easy, Tobirama can do the same thing with FTG, Kabuto can't locate Mu, the sensor snakes are non-factor, Mu hides his presence, therefore, his Smell , Genjutsu wouldn't work on an opponent you can't see or sense. tagged Mu would Blitz Kabuto with cube Jinton while he is trying to evade Edo's GKF, Healing is useless in front of Jinton , Once Kabuto is tagged, he is dead.
sure it's all IMO, Kabuto has his chances.