wishiwasupthere - I think it is called FINAL because it does not fulfil the function of a DIRECTOR, the aircraft are already intercepting final approach they do not require "directing". It seems to be the equivalent of the Precision Runway Monitor (PRM) in Sydney, which listens on the Tower frequency and will break in and provide go-around instructions if required.
In Sydney the positions are staffed by controllers on overtime, so it can only be used when ATC will take the extra duty. This is overcome in VMC by the so-called Independent Visual Approaches, which require pilot separation.
Approach path monitoring is required on all parallel runway operations, in BNE they have chosen to do it differently so that it is available all the time without having to call ATCs out or impose visual separation requirements. Hence they are called Independent Parallel Approaches with no requirement to include visual or switch on a separate surveillance system (PRM), as in Sydney. A PRM system is not required in BNE due to the runways being 2000 metres apart.
My question would be, why are the aircraft not transferred to the Tower frequency from Approach, with FINAL just listening-in as in Sydney.
This would seem to introduce a late change to the Tower frequency where important information might need to be passed, such as RVR in low visibility, or other information.