'Overhead the concrete the sinkrate still increased remarkably and I had to yank the side stick back to its mechanical stop to break it.'
I am not, for a moment questioning your technique but I do find it amazing you would have to ever go 'to the stops' with your flight controls.
Is this not that unusual on the Airbus and is it a case of having to put in more input than is really needed to ensure the Aircraft reacts in time after your inputs are 'filtered' through the flight control system ?