Another example of the arguments of the brigade I was referring to and Clandestino's reply :
We have three indepentent systems, each required to be very reliable. Suddenly two of them simultaneously fail in the exactly same manner and their false outputs are diverging from real values with the very similar amplitude over time. I didn't take this scenario into consideration as my opinion is that chances of its occurence are virtually nil.
There was, Clandestino, a more to the point answer, IMO : That this kind of failure is more likely to happen -however remote it might be- on a Boeing FBW as the boxes are the same. Airbus had these computers made by different electronics manufacturers in order to augment the un-likeliness of it happening.
But of course, Boeing products are totally trouble free, aren't they ?
As no one had taken the hint I made, just look into the description of a chandelle...or ask the 320 TRIs who've performed the required manoeuvres for a post-maintenance acceptance test...and compare these to the two-surfers' witness reports...And then re-read the Airbus recommendation, past the static port bit.
Still no clue ?