I dont think Pedro is more replaceable than Varitek. If anything, he's less replaceable in my mind. We have Shoppach coming up in the system, and although there might be a gap between him and Varitek if tek doesnt re-sign, we could make do with a poor catcher, most teams do.
But Pedro is the best pitcher in the game, hands down. He's irreplaceable pretty much. None of the free agent pitchers are anywhere near his calibre. But if the sox got millwood and morris, and lost Pedro and Lowe, then I'd consider that addition. We pick up two good pitchers, and lose one great one and an ok one. But both of those players would carry big contracts, so nevermind.
And D-train, eh, I don't know. I'm still undecided on him.