Since the ballistics are better than the 5.56/223 round they are good for hogs. I have shot several with the 5.56. But I also have personaly witnessed one shot kills on deer at 150 yards with the 6.8. And 75 yard -100 yard kills on pigs. Of course I am a shoot the pig behind the ear guy! Not that the 6.8 is my prime pick for deer caliber but it will work well enough. And will work on pigs!
I also the 6.5 Grendel is a fine caliber and I like it very well. But the 6.8 ammunition is much easier to come by over the 6.5 and the 6.8 is good to get that extra over the 5.56.