BM,
ADS-B is more accurate than radar (primary or secondary) and is far cheaper to install and maintain.
The great leap forward is that a cockpit display can also be fitted that gives a GPS like traffic picture on a moving map display to the pilot as well. We had a great demonstration of this in Brisbane earlier this year. This makes ADS-B great for pilot situational awareness.
Australia is leading the world in the implementation of this technology for Air Traffic Management. It will go a long way towards making the concept of free-flight a reality in the future. We are already conducting trials on behalf of ICAO to establish separation standards for this technology. Another area of aviation where Australia is not waiting for someone else to lead the way (yes I'm having a dig at USA with their outdated ATC equipment and reliance on radar).
I'm surprised Dick hasn't leapt on to the ADS-B bandwagon as it will enable inovative ways to better manage Australian airspace. It should bring big savings to every section of the industry, not just the big companies.
DP