Adam,
Thanks a lot for the this new series. I learned so much about processes and scripts I never used before. It will change my workflow, especially incorporating ImageMerge into the flow.
I was looking more closely at the parameters of Gradient Correction after watching the videos. I checked the "Automatic Convergence" checkbox using all of the same values you used on the SuperLuminance image and it converged after two iterations and did a better job of removing the "star halo" on the right side of the image. I didn't notice any real negative effects elsewhere in the image. I think it's worth at least trying this (or maybe just re-running the process a 2nd time).