I have fished the Hawksbury for some 25 odd years since I was knee high to a grasshopper, and although it has declined in fish stocks somewhat, the river is still definately alive and producing some great fish.
As others have posted its a matter of having a plan for the day and targeting specific species, I have fished up some PB and won comps in my fishing club sveral times with some fantastic catches in this river.
Pinkies or nippers seldom will hit the bottom if you have bream on the bite and yes definately try SP they are a great alternative.
Don't be one of the people that sit with the masses around flint and steel all day waiting for something to commit suicide on your hook, move around and defiately use berley if the fish are not on the bite, but I tend to find that over use of berley in this river just seems to attract the rubbish.
I know it's not always an attractive alternative but try hiring a tinnie and talking to some locals, it's amasing what info will be devulged when handing over some cash for a days hire.