the only device i tried was a LADDERMAT. heres my warning,it suddenly slid out on me and i fell the full drop/ i survived by sheer luck
i contacted the inventor and he then got a bit shirty with me because i posted on the forums about what happened. then other forum posters wrote telling of other near misses when these devices fail,
lord knows, if you die theres no proof to tell what happened on the day the "safety gizmo " turned out to be total Sh/t