One would think that the capacity should be higher in segregated mode, as the traffic flow is less complex
The most efficient use of the runway is for aircraft arriving and departing on one runway.
Compare Gatwick's hourly rate of well above 50 compared to Heathrow's 40-45 per runway. However the complexity of integrating traffic at Heathrow will give a movement rate somewhere between the present 87 and below the theoretical maximum of 112 per hour.