Man, I was reading this thread and was surprised at all the emotions. Chill out people, if some dude post stupid shit, just don't reply.
If you want me to print some things out and test them I will for a new dynabar
I've been printing for 5 yrs. My opinion is any typical material will wear out quickly regardless of the infill %, but I'm only about 80% certain on that. If you have evidence of it working on a ring I'd like to see it. I'd also be careful of liability. Any printer knows layer adhesion, part orientation, etc, can be an issue and certain batches of filament can cause problems. 3d printing for functionality needs to be done with care. Those rings I think are going to wear out fast in anything other than nylon, which I don't have experience with. Nylon needs too hot of extrusion temperatures for me. The pulleys may last, but I still bet they wear out. The quick release pull would be my greatest worry about getting the print correct. I've printed stuff out for a 4 ton press stamping on stainless steel and it has held up for months, but this is not friction, damn fucking strong tho I tell you! The friction pieces I've printed out have not held up.
Regarding the 3d printed piece for the rope...I've tried this and it does help for a while but the plastic wore out. Your parts are a little thicker than mine, but I still see the same outcome. I smoothed out the dynabar holes nicely with a dremel tool and I don't have any issue with dyneema strands breaking or getting cut at all. My rope always needed replacement before this was a problem anyway. I suggest adding another rope with extra slack in case your main line breaks...
Here is a fin I printed that has lasted a year. I can't remember but it was about 50% infill. 100% is not feasibly for a few reasons...the most you want to go is I'd say 95%. I'm also in the middle of a big foil project and we are starting by doing a functional mold for a stabilizer to test on my foil.
All in all, I encourage the process you are on, but make sure you have some field tests on what materials work and if they are wearing out slowly or holding up rock solid. Good luck, if you need any field testing dm me.