I would say that grits rates up there with oatmeal for carbs and fiber-- or are they more like pasta meets bread?
Either way, if you need carbs in a spot, I don't see why they would be a problem. As long as there is no hydrogen. oils/fructose, and you balance consumption with quality protein.
grits are just highly processed corn. they are on the glycemic index right next to white bread (which we know isn't the best choice for carbs), so i'd recommend that you only eat them sparingly.
(they are freaking good, though, especially with a little dab of butter and some nutmeg)