So here are a couple of shots done for non-scientific comparison between the pre-aspheric (e46 version) and aspheric versions of the Summilux 50. Both shot at f1.4 at a distance of 0.8 meters. It's kind of a worst case scenario - using the largest aperture at near the close focusing limit. It does show some of the differences in both low-value and out of focus rendering between the two.
More specifics: shot on an M8, both with UV/IR filters attached, lens detection set to "off", daylight white balance set, and using manual exposure. There was a slight rotation of the camera on the tripod head when mounting the second lens, however the tripod itself remained stationary. The pre-aspheric shot appears first.