Late jumping in here, but I think this thread really highlights how little we actually know about Orochimaru's body hopping process, thanks in part to the fact that Living Corpse Reincarnation had its entry in the second databook, when its true nature was still being kept a mystery. Though in reality this thread is probably putting more thought into the specifics than the author ever did, especially since it worked completely different the second time we saw it.
One thing I'll point out about the "true form" debate is we don't actually know where the snake body comes from. The Living Corpse Reincarnation article currently claims Orochimaru has to discard his current host body to resume his true form, but for all we know, what we saw in chapter 344 was just a standard use of this technique and he was still possessing Gen'yūmaru until he transferred into Sasuke. After all, it's not like Kabuto had to discard his own body to enter his snake form, he just used the shedding technique. This would also mean it was technically Gen'yūmaru's flesh that was grafted onto Kabuto and later used to revive Orochimaru. We know Orochimaru's chakra can have an actual physical effect on a person's body, since his eye markings appeared on Sasuke when his chakra started rising to the surface (though strangely they were absent on his female body in Part 1).
My point is, there's a lot we don't know about this stuff and we probably shouldn't presume anything, no matter how small. After all, other commonly held fan beliefs about Orochimaru have proven wrong over the years, like his soul-arms being fixed when he swapped bodies, or Sasuke's snake summoning tattoo/contract only existing while Orochimaru was inside of him.