arnold toon shader with | motion blur

… raises several questions.

aesthetically correct seems that despite the leg to the front is blurred a lot (1) and the leg in the back not at all (2) the edges are not blurred on both legs. motion blur seems to not affect the black silhouette lines.

but why is the silhouette of one leg (3) thicker than of the other (4) ?

and what does the shadow (6) have to do with the delicate black lines in the rear leg (5) ?

finally: why is the reflection of the silhouette of the front leg motion blurred (7) ?