I have the 1.1 Rev PCB (batch 2) and whit cpu at 640MHz im getting 470-510GH/s, the pool inform 450GH/s without update the firmware.
I am also 1.1 Rev PCB (batch 2), but with newest firmware. I've was averaging about 425GH/s at the pool. I upgraded to cgminer 4.0.1, but went down to 345GH/s - 385GH/s at the pool. So, I went back down to cgminer3.9.0h2. Everything has been fine since.