Just following up - I cancelled my Chase tickets on the Delta app about a week after booking, and got normal Delta e-credits back in my account (and for each of my family) - so it was a way to turn Chase points into Delta credits that I could then fully control. Not worth doing if you are at 0.01 value as you could just do the pay yourself back approach and avoid all of it, but if you have any remaining 0.015 legacy points, there's some benefit