Do a Run and Break when the circuit is clear and you are affecting no one, it is after all just another method for joining the circuit.
Completely agree. The problem comes when the circuit isn't clear, and people clearly still attempt R&Bs in this situation. I still do not really understand what another aeroplane would be doing if it declared that it was doing a run and break, and I bet many (if not most) PPLs are in a similar position.
IMHO, a run and break is different from aerobatics - if you fancy looping, then find a quiet bit of sky, tell whoever you are talking to what you are doing so they can tell other people to avoid you, and get on with it. A run and break is in the circuit environment. If it's empty, then fine, go ahead. If it's busy then give it a miss.
Places like North Weald aren't the problem - plan a flight there and you'll notice the warnings about high-performance aeroplanes and find out what is going on for yourself (I'd ask what they were likely to do when calling for PPR). The problem is at the places where nobody has a clue what a run and break is.