If he just tranfer the mind, everytime, when he transfer his body, he need to cut his old body and get his sowrd back, and eat it back....
- may be (eeee.....)

When one summon an animal, s/he needs to have the contract with the animal with the blood... As orochimaru only transfer his mind, no soul, there is no way the contract can realize the "stranger", so orochimaru need to re-make the contract?
- may be, the the scroll will full of his name soon (smile)

If he just transfer his mind, why he need to wait for 3 years? (Ino seem can do it everyday), It does not make sence if it is only the mind without the soul.