I have always been on the side of removing the Mustafar sequence
But the idea of moving the Vader helmet scene during the opening, it could sell the idea to me for keeping it. Plus … even plot wise it makes more sense especially since Kylo went to the helmet AFTER is contact with Palps … so why consult his “grandfathers” guidance knowing its not him with it being Palps behind it? Didn’t make sense.
The other benefit of it being moved is it frees things up with Rey and her “dark” version … which the audience member could connect that since Palp has “revealed” himself she is getting this vision or whatever … kinda like the flood gates have opened or something.
Anyway, I am liking this idea of moving that footage to earlier. I may play around with it myself.