Could it not be argued that the extra runway length will reduce aircraft noise due reduced power settings for departure.
It really is quite funny how much fuss there is about the noise factor at the City when in real terms so few people are effected in comparison to virtually any mainland airport one cares to choose. Reading this thread through the years it is obvious that even if all the aircraft using BHD were completely silent and invisible there would still be complaints about something, some people just love a good whinge!