another interesting fact that I just rediscoverd from reading the fight with the third again.
on chapter 121 page 2 the third sais that edo tensei is not dispersed even if he killed orochimaru.
so I think that from this we can also conclude that the actions of the summond one no longer depended on the chakra's of the caster, and thus is not a drain of chakra for the caster.
and so far we only know that sealing the soul is a working way to defeat edo tensei, but somehow I think there must be another trick to defeating it. one we just don't know about yet.
only 2 options I can think about at the moment (purly theoretical with no basis at all I admit)
1) perhaps it has something to do with that funda tag that they put in the head. perhaps if you can remove or destroy that the soul will be cast out of the sacrefice body
2) or if you can completly destroy the body of the sacreficed person that houses the summond soul
just a though, feal free to smash it to smithereens
