I'd swear I saw a post somewhere that pushed the rate down to 400GH and ran even cooler, and with better efficiency. The Monarch really appears to have been more like a 450-500GH miner, which came pre-overclocked to try and save face for BFL. The whole PCI form factor, which then forced liquid cooling, were major failures along the way (IMHO).
With the proper settings / codes, I can get it down to 40GH/s .
I prefer 500GH/s though as it still earns some BTC and runs cool.