[Alan Roehrich]

Pushrod stiffness prevents the pushrod from flexing, and putting its own flex and dynamics into the valvetrain. The rocker cannot even begin to do the damage the pushrod can, the pushrod becomes a spring that flexes and surges, then transfers all of that into the rest of the valvetrain.

Unless you try to make the valve end of the rocker out of lead, you're not going to make the rocker arm heavy enough to make rocker weight into a negative factor.