Why would having more aircraft in the system, showing on the same TAAATS screens, reduce staff.
There is a perceptions that this is the way it will work; the amount of controllers currently needed for the current non surveillance 'sectors' will reduce with full ADS-B coverage.
But then there are technical issues. Such as the size of the displays and the ability of one set of eyes to effectively scan it all. If you are able to use a 5NM ADS-B standard why would you monitor a display of 1000NM or more; it's not terribly practicable.
Other trials have proved that much more traffic is displayed, as such the 'duty of care' of the ATCs involved increases, so whilst the 'conflicts' require less workload because you can use radar like separation instead of procedural standards; the workload associated with 'extra traffic' is significantly increased particularly close to busy aerodromes.
ADS-B will have significant ability to increase safety, but will it reduce ATCs? My best guess is not likely; particularly given we are the best part of 100 short now, from full compliment, and there are significant retirement pressures coming.
I too like Dick Smith, would like to see the 'business cases' with all the options laid out openly so they can be publicly critiqued before the decisions are made. "ASA has form, none of it good".