That one's getting the Grendel soon.
After this thread got going, I looked around and found the ammo stuation was better than I recalled it being before, so now I have to say it looks like the Grendel's only real advantage is at long range. I can't recall reading about any tack-driver 6.8s, but that may be related to the rifles involved.
For now, a Contender looks like the easiest way into a non-tactical 6.8.
