I was just reading the comments in the L.A. Noire review and saw that there is an unexpectd benefit to disc swapping: Sharing!
Some guy said that he didn't buy the game. He borrowed disc one from a friend and is playing the discs as his friend is finishing them. I guess it was pretty obvious but I never even considered this! So my friend, Jake (D11) was interested in L.A. Noire. I can just finish disc one and loan it to him without a care in the world. He can play the game without spending the $60 that I spent and I can continue playing it, too. Pretty sweet!