I have a left hand Stag in 6.8, 2 uppers, one a 20 inch barrel and just picked up a complete upper with a 16 inch barrel. Both are very accurate with the 20 being the most most accurate. Both the Grendel and 6.8 are 300-325 yard guns on medium game. There probably isn't a knat's worth of difference between them in those ranges. The 6.5 bullets have better BC's and as such would perform somewhat better over 500 yards. I rarely shoot that far.
So that said, I have a 6.8 and no need for a Grendel.
