in empire strikesb ack, vader knows about skywalker. its nice our imagination can fill in the blanks as to how he knows.
too much is as bad as too little.
take the wampa example. in the original ESB there's tons of menace because we don't really see it. its hints here and there, rather like a horror or jaws. come the SE and you see lots of it and it spoils things in a way because it takes away the menace. for me, the same rules apply here.