I have the same processor and I am able to get over 13,000. I would say make sure you're are using the Omega 2.5.90's which are based on the 8.07 hotfix(or 4.10 BETA), or the 8.07 hotfix itself from ATI. Same driver just different interface. Hotfix uses ATI control panel, while the Omegas use the radlinker. I would not use the latest Official Cat 4.10 as it actually based on the 8.062 driver set, and doesn't have the memory fix.
And your oc's are fine..I don't even take mine past 545/565. Do you know if you have the 1.6ns ram or the 2.0ns as windom had asked? To tell just look at the chips, the last numbers will be either 16 or 20 if you are using stock cooling you might be able to get it a little higher by using an aftermarket cooler such as the Zalman or the Arctic Cooling ATI Silencer 4. Other than that lower benchies could just be due to settings or maybe the motherboard what are you oc'd to on the cpu?
edit, you type too fast...lol. What power supply are you using?