it's averaging about 192 gh/s now - up from about 178 - perhaps I should have done some cleaning when I got it - but it's tucked away in a cabinet now in a data center and the luck of shush's pool is being good to me - so I'm not touching it now.
That's a very good idea, it's amazing how much dust these things pick up and a clean once every 3 weeks makes quite a difference, but if it's in a data center it shouldn't be as much of a problem.
FWIW: I get 203Gh/s at 400Mhz with decent extra cooling.