Yep, played with GA and NN's quite a bit. The biggest trick is getting the mutation code correct. I wrote an article about the topic for Delphi Mag a while back, unfortunately it never got posted as it was to long. I'll have to look around and see if I can find a copy.

BTW: A good thing to look at is storing the weighting method as a pointer and choosing random starting weighters. Then you can use that as part of your mutation in a 1 of n scale. Its very interesting how the results change and the curve modifies when you use this method.