Sorry, but it may be a bit late, but I have just read the front page of the Registax website
http://registax.astronomy.net/
"
New: improved image-quality estimator
Pushed by Anthony Wesley and Damian Peach (independent) there has been substantial work and testing of a new idea to estimate image-quality. The current implementation is largely based on the initial idea of Anthony Wesley. The new quality estimator is called “Gradient”. Without additional controls it is very simple to use."
No wonder Damien has been stealing your ideas re cooling 
Well done!