Orrochimaru means snake in japanese ....orchimaru has always been nuts about snakes.... thats why he chose that sage because it fits who he is..... he didnt choose it for power advantages lolWho know the differences from one sage mode to another. If Oro REALLY wanted sage mode then he could of taken over his old buddy's body. There must be some sort of difference in the Sage Modes to make Oro want this sage's mode. If Naruto looses control he petrifies. If Kabuto looses control he goes berserk. In addition the imperfect SM j-man has toad features and this mode can be preformed with anybody with a large chakara supply. Kabuto also seems like an imperfect SM(still looks snake like) and it augments his personality (cursemark/Jungo) in addition you need a special type of body to preform it (this is why Kabuto stole jungo's nature absorb, Karins healing/endurance)
We know there wont be a Kabuto vs naruto because Sasuke wont retreat or die and if Kabuto retreats he may tell Tobi then Tobi may get pissed and try to fight SasukeSo basically, since Kabuto has a Sage mode, Sasuke will be able to tell how to counter it once Kabuto is defeated. When it's time for Naruto and Sasuke to fight, Sage mode will be of little surprise to Sasuke and he'll know some of the benefits it gives Naruto. (F'ing Kabuto)
I know some people will say Kabuto may not be defeated by Itachi and Sasuke in the first place but honestly...it's Itachi and Sasuke. They are both taticians in battle and I'm sure they'll find a way to beat him...Kabuto basically spent the whole manga chapter explaining his abilities. Don't you think they'll come up with a counter? As Itachi says, every jutsu has a weakness. I don't think there will be a Naruto vs Kabuto fight.
Sorry for getting a little off topic there but as a last note, I just hope Tobi doesn't say anything to Sasuke about Naruto's Biju mode; if he does, then Sasuke will know about both transformatons and have an advantage. :sy: