Further on the loading issue a dispatcher at LHR told me that with not more than about 85 passengers worth of bags it is possible to load them entirely in one of the holds on a 319 meaning you can use one hold for outbound and the other for inbound which in turn means that the inbound and outbound baggage can be loaded/unloaded simultaneously, effectively halving the time required.
Systems falls down when the baggage weight beomes too great though.