Not to beat a dead horse here, but it seems Lucas created the new Vader and Palpatines lines to forshadow the big reveal later in the movie.

EMPEROR: We have a new enemy, the young Rebel who destroyed the Death Star. I have no doubt this boy is the offspring of Anakin Skywalker.
VADER: How is that possible?
EMPEROR: Search your feelings, Lord Vader. You will know it to be true. He could destroy us.

VADER: Obi-Wan never told you what happened to your father.
LUKE: He told me enough! He told me you killed him.
VADER: No. I am your father.
LUKE: No. No. That's not true! That's impossible!
VADER: Search your feelings. You know it to be true.

I think that the idea behind the new dialogue is interesting, but the wording along with Ian's delivery don't make the SE change an improvement to the original.

Beating done.