I think the real big difference is frictional loads, at low RPM the flow theory stuff probably wins out but add in high RPM long stroke and friction begins to win out. Look at the rod angle in a 400 SB chevy at 1/2 stroke and see how it would be forcing the piston into the wall then look at a 340 under the same condition and the visual difference is tremendous. It is very easy to see how the friction goes through the roof with a bad RS ratio at high RPM. Still getting the displacement and airflow up is gonna trump a bad RS ratio as proven by the big bad mountain motors.