Well, I think you can leave Maul as Maul in the first film, because doing so allows for the 'REVEAL' when the camera pans in tight on Greivous eyes. I think using a simple audio editor, you can alter GG voice to a lower, slower tone that will be closer to that of Maul's, but yet different enough as was Vader's. The whole point is to shock the viewer when you get close up and all of a sudden, he is Maul underneath. Even change the blade colors to Red for his sabers and leave the other Jedi's alone.

I too, would like to know what this Obi-Wan edit in the OT is about. :grin.