beatle collaboration specifics

Interesting post on Slate about the Lennon McCartney songwriting partnership (hat tip MM). This anecdote begins the piece (no source is given):

John and Paul did balance and complement each other magnificently, and we can pile example on example. When they were writing "I Saw Her Standing There," Paul offered this opening verse:

She was just seventeen
Never been a beauty queen

"You're joking about that line," John shot back, "aren't you?" He offered this revision:

She was just seventeen
You know what I mean

There it is: Innocence meets sin—an inviting, simple image takes a lusty, poetic leap.

Also, snotty meets friendly. The article has another story about Lennon breaking a washboard over the head of a band member (pre-Beatles) who announced he wanted to leave the group. The Slate piece avoids the sadomasochistic aspects of the MacLen equation--it's more about "friendly competition."

Not that John did anything that violent to Paul (that we know of), but the question remains: "Is improving your art worth having a washboard broken over your head?"