Good day mcjtom.
To find out which is less jammable you could actually test them. And of course the media with which it is tied will have an influence.
I use the Ashley stopper exclusively mainly due to its larger footprint and although I don't think I have ever come near the breaking point of the rope, I have always been able to untie it. Most times it is a permanent scenario, such as terminal knots in the seat of a swing.
My suspicion is that the Stevedore will lose the contest.
