I liked Snow as Namine, because I thought of Namine as a robotic character. She seemed good emotionless to me.
As for Hayden, I'm scarred. I don't want her anymore. If she were to do anyone, then keep her as Kairi. Even if Kairi isn't in any of these newer games, that makes it better. Hayden as a VA should die, along with Kairi.
And with Meaghan, she needs to NOT do this. She's a sucky actress and she needs to go away.
I honestly don't know who should be the VA for Xion. Anyone but Stoner or Meaghan.