I believe you wont be able to go much further than 450MHz except you replace the power exchanger on the board (or how its named). Its already at its limits at 450MHz as far as i remember.
I am aware of that. I posted about it in burnins thread.
I have a couple of 10 chip boards on water for testing. For science!
Ah... interesting... im waiting for your results. I wonder a bit how long the asic's will work anyway with electron migration of higher voltages. Unfortunately no observations available yet... everyone has to bear the risk.