Reeley
S300 correlator is really good and better than you say. If you follow the factory teaching which is
set 2200/2300 rpm with flat pitch. Lift the lever slowly to get to 19inches and 3000rpm then forget about it the rpm will be held in the green right up to about 25 inches. It is only at the top of Manifold Pressure that you might need a squeeze of throttle.
However, health warning it does depend on how good the linkages are !