[Dariusz J.]

Gents, it is about the TORQUE of the shafts, not about the FLEX. If someone witnesses a shaft phenomenon that looks like Hogan's in 'Power Golf' it mainly means that the torque index of such a shaft is too high for the swing parameters. Granted, usually, the flexier the shaft, the higher is the torque, even nowadays, but if the technology permits someday to invent a flexible shaft with a very low torque - why not soon as we are in the nanotechnology era - it would be a dream for clubfitters.
Such a shaft won't look like this as well as late Hogan's "telephone pole" shafts never looked like his pre-secret shafts. IMHO, what Hogan really wanted was low torque, not overhuman stiffness - but in his times it was impossible to tear those two issues apart and he ended with extremely stiff shafts that gave him the torque low enough.
Associate this with the clubheads CoG in relation to the shaft end in a rapid rotary motion and you will have the answer why the clubhead motion can simultaneously rotate and bend the shaft.

Cheers