Okay, I'm going to eat crow now.
GradFun2DBmod shows some significant improvement in banding. I'm having difficulty using it at the same time as my script, due to the fact that the new pre-release of removegrain doesn't include clense for some reason, which I rely upon heavily in my script. I will need to find a work around.
Expect a new version of the script sometime in the future.
-G