What city? What kind of weather do you expect to be running into? Road conditions? How fast will you be going?

Don't worry about the durability: most reputable manufacturers carry a lifetime warranty (excluding accidents that would destroy your frame anyway) on their frames so it's not like your road bike will break because of a bunny hop or two - the double diamond is more durable than you think. (You're more likely to destroy a wheel that way, but that's neither here nor there.)

For instance, I ride a Bianchi Via Nirone as my primary commuting bike: it's an "endurance bike," which means a taller head tube and a less aero rider position. At 22 pounds, it's also heavier than most bikes and feels it: I don't feel road buzz too often, the bottom bracket area feels a stone weight, and it's more sluggish and less responsive than my old 1997 C'Dale CAAD2. It also feels indestructible.