We've operated a CJ3 for 18 months now and I have flown from LAX to Sydney, Oz, but definitely not on the route you mentioned. I went LAX-SEATTLE-COLD BAY-PETROPAVLOSK-KANSAI-KOROR-CAIRNS-SYDNEY. We had headwinds the whole route, longest leg was around 1640nm. This route is full of potential poor weather, long diversions (if needed), long STARS in Japan and being held down in Russia. Combine this with ISA+10/+20 deg for the climb and headwinds and we consider 1640mn is the most we plan with certainty. 1000lbs is an absolute minimum for this type of route. I prefer more fuel for these routes (compared with flying at home) not less. 400 lbs would be, in opinion, far too low.
The longest leg with have flown is 1977nm with good tailwinds (circa 50kts) and this is going straight to FL450 and operating at absolute optimum SFC. We landed with 1100lbs, so no problem.
The aircraft does perform a little better than book, but conditions are never perfect and you have to consider the emergency descent scenario.
I hope that helps!