Everything points to the fact that performance wise, all the current "Sport" dynamos (above the 3N30) are identical. Most of the current hubs have been tested by various German magazines, and they all come to this conclusion.

All the 3N80/3D80 and other hubs in similar weight range have an aluminium axle instead of steel, and there are other small variations in sealing and cones. My guess is, that the alu axle, lighter hub shell versions like the 3N80 are less sturdy than eg. the 3D72. I have owned a pair of 3N80 since they where released (2008/2009?), and the have performed flawlessly, even with heavy loads, so I don't think they are delicate, just that for off road use etc. the steel axle models are probably a better choice.