Longer buffer is essentially short stroking the gun. Heavy buffer means less recoil into the shoulder and more energy forward when the bolt slams forward. None of that has an impact of changing the rotational torque. So far the general consensus is less reciprocating mass, shorter stroke and fast cycling equates to faster dot recovery caused by less dot movement. How the gun feels in recoil is subjective. My teammate and I run nearly identical setups but his bolt is heavier and his gun is not stroked as short. He actually gets low second hits with my gun as it cycles faster and flatter causing him to overcompensate when pulling it out of recoil compared to his.