hey mr Fanpilot,
assuming forward airspeed is present and a forward cyclic input is applied with the intention of increasing speed the following will occur
advancing blade experiences greater wind velocity therefore generates more lift and flaps up.
this flapping up decreases angle of attack and starts to reduce lift which modulates the flapping up, blade is flapping up at greatest rate at 3 o'clock position and reaches its highest point at 12 o'clock position.
retreating blade experiences reduced wind velocity therefore generates less lift and flaps down.
this flapping down increases angle of attack and starts to increase lift which modulates the flapping down, blade is flapping down at greatest rate at 9 o'clock position and reaches its lowest point at 6 o'clock position.
therefore the net effect is that forward cyclic makes the rotor disc flap up at 12 o'clock position and down at 6 o'clock position which left uncorrected will cause the airspeed to reduce therefore it is neccesary to "push through" the flapback to prevent this occuring.
finally its twin brother "flapforward" occurs when you apply aft cyclic to attempt to slow down and everything happens in reverse.
therefore in my opinion R & K are correct
regards
CF