So stepped things up dual mining SHA and Scypt to 800Mhz, and I am getting 6.4GH/s and 340Kh/s avg per gridseed, they get mildly warm but nothing that i would be concerned about.
Anyone try dual mining under windows at 850Mhz yet, I dont want to push them too far when mining sha alongside scrypt as the sha asics can get fairly warm.