I own both a Domane SL 6 and a Checkpoint ALR 4. The Domane will be fine on gravel. It will easily run 32 mm tires. You can put some protection on the inside of the down tube to keep it from getting dinged up. I personally wouldn't take my Domane on really rough gravel roads, but it would be fine on some mild stuff. The Checkpoint will hold 47 mm tires for off roading or you could put some 32 mm slicks (or smaller) on it and ride it on the road comfortably. There's about 5 pounds difference in the two bikes, so the Domane is gonna be much snappier.
You can't go wrong with either bike. The ALR 4 is a lot cheaper. And btw, the Tiagra on my Checkpoint is really good. It shifts smoothly and the finish on the group set is great. It's not quite as nice as the 8000 Ultegra on the Domane, but it's a dang nice group set. Don't let anyone tell you that Tiagra is not good stuff.