Cool, I'm glad it's working out for you. Due to my workflow at my current job I haven't actually had much occasion to use it since writing it, so I'm not that confident about how good the hueristics are.
Do you generally use the default --strict setting?
I usually do not look through all commits again when a basic review already happend and i "just" integrate the review comments. That is where for me personally these problems happen that git-autofixup is sometimes wrong but in over a few thousand commits in the last months this happend only thrice. Which for me just speaks for the tool IMHO. Ow the original author big time :-)