A few years ago I wanted to test xp2 film. I had the roll next to some rolls of fp4 that needed to be developed. I picked up a roll and loaded it onto the spool. Once I turned on the light and saw the paper backing and realized that I could no longer take the roll in for c-41 processing. So I decided to what would happen with PMK.
To my amazement the negatives came out very printable. The contrast was a little high but still made nice prints. I planned on testing further to hone in on the perfect time and dilution but haven't done so yet. This was my first adventure into cross processing by accident.