Fair enough, I have never used descender rings for that but them not having had the safety knot would make sense. I was mainly stating why I hadn't used them personally with the reasoning and commenting that I knew people who ended up sitting with them.
I'm not jumping on you or anything! I just wanted to point that out so as the OP would have a cheaper option if they are inclined to do so! Many people do not like the rings as they say that they have given out(slipped) and they have gone to the ground, and the reason is that the safety knot (slippery half hitch) was either not tied all together, or not done correctly! The reasons that I switched is because I have a gear fetish, YEA I SAID IT and I also wanted to try and go "lighter" which is why I went to dynaglide whoopies! If not I probably would still be using the rings and webbing suspension!
"yesterday is history, tomorrow is a mystery, but today is a gift---thats why its called a present" - Master Oogway
It's always best if your an early riser!