I actually don't have a problem with any of those, especially Ian McDiarmid's replacing the original Emperor, because McDiarmid rules! My big beef with the Hayden Christensen change isn't the change itself, but the fact he's wearing white Jedi robes (which we NEVER see him wear in Episodes II and III!)
I have the feeling that if Lucas had at least tried to age Hayden up - given him a haircut to match Shaw's, for instance - most of the objections would disappear. The idea was supposedly to see Anakin the last time he was himself/a Jedi; it should have been to see the Jedi Anakin WOULD have been had he not turned. An older, wiser Anakin who had finally gotten over himself and his rebel phase and now fit in with the Order. If Lucas insisted on a younger Anakin, fine, just chop Shaw out completely and show Hayden in his ROTS outfit. No badly done half-measures.
Hell, Hayden's almost the right age now; if they tried deepfaking his face onto Shaw's body today (and this time telling him to actually look offscreen at Luke with a beaming grin and tears of joy, instead of just smirking straight into the camera), it'd be problem solved.