... east vs west, the point is that EDI without proper taxiways still only operates at about 50% capacity, GLA say 70%. There is no need for any extra capacity in Scotland for years (given propertaxiways), in the meantime LHR is operating at about 98% with suppressed demand for probably another 200 or movements a day.
Last time I had the 'pleasure' of operating ex EDI we had a 15 minute departure delay on 06 with no back track required primarily due to incompetent ATC tower controller getting nervous when someone was 6 mile final and not departing anyone in the gap. In that time at LGW they would have departed 1 or 2 aircraft.