And at least now we can understand why he sounds so royally pissed at the beginning of ANH, after the plans only just barely slipped through his grasp a few minutes before.
I always wished he'd stayed more hotheaded like that throughout the trilogy.
Can you imagine if we (Vader) lost Jones AND Prowse? Considering how different Vader feels with this new guy behind the suit, I'd hate to think what he'd sound like with an imitator.