DozyWannabe -
I believe the change was also done due to weight and cost issues. IMO the 'better' system was overruled by economics.
All airliners can rip their tails off. The senisitivity of the A300-600 vs. other airliners is what the union had problems with. The reports I read stated the new design wasn't flight tested on the A300-600. Instead the A310 flight test data was extrapolated for the longer fuselage length of the A300-600. So they end up with the most sensitive rudder(rudder displacement per degree of rudder pedal travel) and it wasn't flight tested???
The early A300 models did not have the same rudder limiter. When the A300-600 was designed the rudder limiter was changed to the A310 design. A300-600 pilots actually get an A310 type rating.
Should Boeing be the standard? IMO it's approach(variable ratio) for rudder limiting should be the standard. I've flown both and IMO it's more consistent with what a line pilot would expect vs. the changing sensitivity of a variable stop type design.