I've been working with a 6.8 for 6 months or so. I've decided that it's going to be my go to rifle for hunting here (TN) since there are very few opportunities for any shots longer than it can handle. Most of my hunting is within 100y most of the deer I've shot are less than 50. The rifle went hunting last season but unfortunately, I didn't see anything to shoot with it.
My son likes it enough that he had me order an upper from AR15 Performance and as soon as it gets here we'll build up a lower and have another one. There are a great many bullets and loads for the 6.8 available. 85g to 130 and I hear that SSA is going to make a 140 Berger load for it, too. There are a great number of companies making barrels and uppers in 6.8. A partial list: Noveske, Wilson Combat, AR15 Performance, Bison, Black Hole Weaponry, CMMG, Stag, RRA. If it wasn't popular there wouldn't be many available. Hornady, Remington, SSA, and Corbin all make ammo for it, too. Neither list is inclusive.