-Remove yoda from the movies, this is crucial and actually serves the OT more because you can leave in all of the lines mentioning master Yoda, setting him up as a great Jedi Master. This is also no problem to me because Yoda is boooring in the PT, save for a few good lines.
This is the only one that I am not sure about. You lose his convo with Obi-wan at the end of TPM, all the council scenes get screwed up, and you lose the meeting with Obi & Bail at the end of ROTS. Plus, then when he shows up in ESB you gotta wonder “Where was this guy in the first three movies?? When did he train Obi-wan???”