... well, actually my concern is not whether to be worried or not worried at all if I have to cycle in Germany; I did it many times and, believe me, I've been always feeling much more confortable cycling over there than in Italy.
My point, so far, is now more technical: what does StVZO says about rear lights flashing, pulsing or, even worse, strobing.
Nowadays I can see cyclists using any type of lights but I wouldn't be much sure that they are totally legal.