My 12 SL with 30K was smooth but my 15 S with 20k doens't take small bumps/variations well. As with others I can't lean my head on the headrest with bouncing.
I think this would be a great idea. The B mode is plenty powerful to warrant brake lights. The argument that people should be paying attention is lame. People DON'T pay attention (I also cycle commute) and in the dark it is hard to judge speed differences. I've driven mostly manual trans...