A.agincourt - the transient effect of moving the cyclic which can temporarily reduce Nr is because you are unloading the disc causing a reduction in 'G'.
Application of positive G increases Nr, application of negative (eg less than 1)G reduces Nr but only temporarily.
Yes it is easily demonstrated but it only lasts while you have the reduction in G. This has absolutely nothing to do with the migration of the driving section of the blade which happens when you raise or lower the lever.
According to your theory, if you start at 60 kts in auto and then increase to range speed (say 90 kts) in auto you will see a permanent decrease in NR which just ain't the case.