ON TOPIC:
wow.. i was under the impression that every one was aware the edo was changed and improved in time...
OFF TOPIC
madagara edo and the kages edos are the same except the fact they don't have the eye powers.
madagara WAS NOT able to free him self. In the moment all edos were released he created a new spell that allow him to control his own actions and of the edo he was because he knew how to do it. (basicaly any edo that knew how to do it could do it WHEN AND IF the edo was released , kabuto did point out it was an easy jutsu)
Note: even before all edos were released by kabuto Madagara had freewill over his actions because kabuto DIDN'T try to suppress them