I'm working on something like this for the next evolution of the entropy visualizations. I've toyed with compression, but have had nicer results so far with other randomness estimators. I'll do a writeup once I have something to show.

For a continuous compression function your idea of running on a rotated or reversed version of the file and then taking a minimum is a cunning one! Right now, I'm still working with sliding windows, but I'll keep it in mind if I turn back to compression.