We have found with the sheet racers that not having enough roll control for low speed flight and to counteract wind conditions is as bad as having too much. I think 1/8" up and 1/8" down should give you enough to be smooth. The servos will last much longer than if you set the plane up with more throw than you can use also. You can always crank up the throws a little to suit your taste buds after you see how the factory approved settings work.