I appreciate your answer. Well thought out.
As far as cut and dry, not necessary, but still would like to hear any known failures in this community caused by rope.
Most people aren't pushing the frontier. Or they get lucky (or test thoroughly as recommended) and experience their failure in a safe situation.
And as Kyler had mentioned - the limitations of where and how you can "safely" push the bounds by using accessory cords...is largely determined by attachment method. If tieing in directly - that's knot strength. If you're using a friction hitch, it's the strength of the cord you are hitching, PLUS how well it grips. If you're using a device (i.e. ropeman) it's the failure load of that device on that rope.
Assuming your prusik grips well, and is assembled in such a way that you aren't loading up e.g. a single knot on a single strand, the load rating is less than generally recommended for life support, but in excess of what a ropeman gives you. Make of this what you will.
I see groups making iffy calls in 2 different directions. Guys moving away from using ascenders to using ropes, but demanding way more from the rope than they ever did of the ascender (and continuing to use what's likely a weaker solution due to "community acceptance") are definitely out there, but the more dangerous group is those trying to shrink down without really having a handle of the risks and true strengths of their gear.
And also note: as you get to the smaller cord - the most advanced stuff generally has the most pronounced limitations. Knots slip. Fibers fatigue. Etc. You can get a 5mm cord with like a 21KN rating. HOWEVER - 1) *** do you use for a prusik, and do you trust THAT? 2) At least one such cord appears to lose up to 60% of its strength in a fig 8. 3) That same cord lost half its strength in 200 bend cycles (and almost 40% in 50 bending cycles or less). We bend the crap outta our ropes at the same/similar points in many of our applications! Does that stack with the knot loss (and all of a sudden your 21KN awesomecord is a 5KN deathmachine after a hunt or 2?).
Honestly we really need to do quite a bit of controlled and semi-controlled testing. Not just take some fresh cord and try to jerk your ATV. But loading and modest-cycle fatigue tests of the ropes, devices, and knots that we put our lives on the line with. Moving to the smaller than 9mm ropes gets us out of device spec, and moves us toward more and more high-tech (
you can often read that as high tradeoff, or "highly steep drop once you hit the limit").
In general - I'll trust climbing-rated nylon/poly ropes to behave predictably and consistently, within the rating given. The tech ropes and cords? I prefer to get specific manufacturer recommendations, or hunt down 3rd party tests of specific products, unless I'm relatively comfortable with assuming it's about half as strong (before knots) as advertised and/or have a plan in place to avoid potential issues (i.e. limit reknotting, cycle through ropes more quickly, etc.).
Honestly we could really use a saddlehunter.com test lab with tensile test, drop-test, and fatigue/bending cycle validation. Especially for those moving away from the (generally reliable) nylon stuff to the latest lighter, smaller, stronger
* ropes and cords available today.
