Thanks for the suggestions!

I love your suggestion about making the audience think that Vader is a different guy from Anakin. I was afraid I'd have to cut Vader in armour at the end of the movie, but that could work really well - especially if I took other Vader lines for his conversation with Sidious at the end.

Grievous will definitely be more BA. He doesn't get his hands cut off and his voice will be more menacing. (Still working on voice)
But given the source footage, it's a little difficult to make him die in a more epic fashion.

I'm working in HD.

And don't you worry! Making it match the OT is one of my highest goals.