It's not as minor as you are implying. It's noticeable if one knows what to look for. The force is smaller with smaller propellers, but then so are the airplanes they are pulling...

Why do model pilots often have the wing banked to the right slightly on climb out after takeoff in order to keep the airplane from turning left during a straight climb, even if engine right thrust exists (instead of applying right rudder which is more efficient and proper)? It's primarily due to P-Factor and spiral slipstream. And why is it that an airplane never pitches by exactly the same amount and/or direction when flying knife-edge left and right? It's not just due to minor asymmetries in control geometry. It happens even with very carefully set up acro planes. Also, it's consistent with the observation that Bob's airplane always yaws left.