I think that there's no conceivable way that cutting Night's Whisper for Thirst for Knowledge could be considered a bad idea.
Nope. There's a lot that I need to catch up on since I took a year off (again), but that's so obvious that it hurts. The issue is that it will have ripple effects through out the deck, which also need to be considered given whatever else is out there to face.
And just like any other deck, once those determinations are made, it's time to weigh it against similarly paced blue-based control decks to see if it's just plain ol' worse.
But yeah, Night's Whisper as a card can go back into the 'maybe someday' bin.