I'm a Campy fan, too, and a bit of an anti-Shimano bigot, too, but Dura Ace is as well made as anything ever made. You'd be switching only for emotional reasons, not functional reasons. It will outlive you, so replacing it before you're dead is premature.

But if this is something to own just for the sake of it, then toss your money by switching to Campy. Hey, maybe you can even make a profit on it. Sell the Dura Ace parts one-by-one on ebay. Buy a complete group from Ribble, who sell Campy stuff at surprisingly low prices. If I were able to do that, I would seriously consider it. You could even break even before all the Dura Ace stuff is gone.