If Rosamund pique, lúcio played Lizzy and Keira Knightley played Jane- would it be much better or worse ???

worse, because lizzy is a sweet but stronger young women and I thin jane just sweet. I like the 2005 version: keira as lizzy and Rosamund as Jane. the best adaptation

Worse, I think. It's just perfect the way it is.

I think Keira was a perfect Elisabeth. She is perfect for that rolle. I can not imagine R.Pike as Elisabeth.