In my opinion, I don't think you should remove the new Boba Fett voice, it works very well. As well is keep continuity with the prequels, something I know you want. I don't think it should be removed just to remove it. It could be argued that if you were going to keep the old voice for Boba you should keep the old voice of The emperor. In any case it's a keeps of revisionism that I don't think hurts the film in any way.