@vilas
I am well aware of the advice in the FCOM.
My opinion is strictly personal, but is based on having read the reports, and seen the flight data from those reports where people have used speedbrake, idle thrust, lifting the nose etc.
Airbus has to give advice like this, because they cover any overspeed.
I dont think my company has seen any excursions higher than 6 knots in the cruise, and the observations were quite clear.
People exacerbated the situation by intervening, and you were left with the sensation that they would have been better off just leaving the A/P+A/T to sort itself out.
(However you cannot know of course, it is speculation, albeit qualified.....)