I believe the reason the military dropped the M14 was in part because it was difficult to control when using automatic fire.
Given the recoil of the 6.8 and 7.62 are similar this problem will likely surface again.
I carried an automatic M14 the whole 15 months I served in combat in Vietnam. I was 21 years old, weighed 175, 60 inches tall. I had no trouble at all carrying or firing the M14 and full auto was quite controllable - when I used it as ir was intended: firing from the prone, using a bipod and the folding buttplate on my shoulder.
Ignore the “experts” who demonstrate automatic fire from the standing position.
Only idiots fire full auto from the offhand.
The M14 had punch, shot with precision and killed what it hit.
M14s in stock as-issued form, were good enough for average Marines to qualify as Sharpshooters (213- 219 out of 250 points) on a known distance range, with a max distance of 500m. I have successfully engaged the enemy out to 600m myself.
The really important part of the M14 was its dependability: it always fired, in heavy rain, dust storms, and weeks without good cleaning in a very filthy environment. The 7.62mm NATO round dependably punched through walls, gravestones, heavy foliage, whathaveyou, and killed whatever was on the other side.
I have also successfully used the National Match M14 in Marine Corps competition in all weather, winning several times (one gold medal, one bronze and two team trophies). My match M14 never failed me and that fiberglass bedding didn't need pampering.
In short, yet another enthusiast for the goofy Stoner design, which is a fine rifle for the civilian range and the gun safe - but I will always be skeptical about any military action that doesn't allow easy access to the chamber and is made of aluminum.
When your life depends on it, wood and steel, baby!