I've never seen a gravel road that was sufficiently well-packed and smooth to make riding it with a road bike anything but a pain in the ass. If by "gravel" you mean a bunch of tiny pebbles around 3mm in diameter, then you could handle a bit of that. Even then, traction will be poor and you'll want more rubber on the road if you'll be riding more than a short stretch of it. When I hear gravel road, I think dirt covered with rocks that are about 4cm in diameter. If that's the case, you're not going to fare well on 23mm 100psi tires.

My own personal thinking is, if more than a half mile of your commute is rough stuff, leave the racer at home. And I don't say that to diss commuting on road bikes, because I do half the time (like today).