I would tend to disagree with that opionion. My brother has a Funtana 40 with a OS 70 on it not enough all out power for hovering. You may want to try a 13x4W to get some extra RPMs you havent said what it tachs out at with the 14x4w. If your spool time is lagged but the plane has enough power to fly with then I would say try the smaller dia prop. if in fact spooling up is quick and responsive then I would tend to say this plane is too heavy for the engine. Your thrust to weight ratio for a good 3D machine should be 2:1. A saito .82 or even 100 wouldnt be a bad idea. The Saito 100 weighs as much as the OS 70 does. Then you could use a 15x4W man talk about prop wash no issues with rudder authority anymore. PS. My brother is currently using a Saito 100 on his and it has cured all issues. If your plane has weak rudder authority then it should no matter what pitch it is in weather straight up or falling off pull out when you throttle up, no questions asked. To address the rudder itself keeping in a hover will be very very difficult if indeed there isnt enough authority. But it shouldnt fall off and not pull out when you throttle. You may however have 2 separate issues that need to be addressed individually. My vote goes with the power. These planes have an oversized rudder so you can hover and I have never seen one that couldnt because of the rudder. Although I am not saying that it has never happened. Clearly MO