I have an October Saturn currently running 612/589ghs through cgminer and 585 through KNC's gui. This is far and away the absolutely highest numbers I've seen (for me and this machine), by almost double.
Thing is, it's doing no good. Error must be bad. WU is only 1450ish.
Poolside reporting is tragic -- looks like about 185ghs.
If someone can help me figure out how to make use of this apparent speed/reduce errors, I'll leave you a nice tip. I don't have enough knowledge and must resort to bribes.

Not every die is going to enjoy being overclocked. Use something like Bertmod to see which dies have disabled cores due to hardware errors. Using the per module, per die script, return troublesome dies to their original clock setting of 1D1 or whatever yours was. There's no strict rules. You have to experiment to see what works best for your machine. If you PM your Bertmod per module stats and your script, I can recommend clock settings.