Some random thoughts, Mini -14 gas system vastly different than M-14.
Bullet and any related barrel harmonics are long gone by the time the op rod bottoms against the receiver, so snake oil salesman talk from Accuracy Systems
Slowing down a Mini is a good idea in general.
Article pretty clearly stated difference between NATO spec 5.56X45mm brass and 223 Remington brass was perhaps 1 % and the difference if any was negligible. Glen Zeidecker his book The accurate AR... He's a high power guy, did exhaustive testing on 223/5.56 brass and found them the same. Not a lot heavier. My own testing has proven this out as well.
As to max loading, everyone has their own choice to make in that area, and a novice reloader better do his research, and not rely on others info good or bad.