I don't see the problem with having your ability to hear traffic behind you slightly affected. At least when wearing headphones you are aware of that and don't rely on your ears. Now that electric cars & trucks are becoming more common you need to look over your shoulder anyway.
With Dammit, speed should be lower on most roads, especially inner city, but not on dual carriageway/motorway. (Actually motorway speed limit seems to be irrelevant anyway, doesn't seem to be enforced at all).
Can we do one of these from east to west.