So what is the benefit over one ring/ biner girth- hitched on the eye of a butterfly?
Do you mean where the ring/biner/quickie is attached to the rope?
I like to plan routes where I can descend from my tie-in downwards. I find in some trees it's more efficient for me to redirect through branch unions and not plan to return from where I came from. By the time I'm on the ground I'll have taken multiple redirects. If my canopy anchor involves tying hardward to my line, as I pull it down the angle becomes tighter and tighter and can be impossible to pull my working end through.
I have used a single ring, knot blocked. It works okay. I was hoping to come up with a mid-line attachable alternative. I made a flint locker type system with a quickie, sling and ring. I can take it apart and use the parts for other applications, so I feel like it's fairly cost effective.











