I am thinking you are suggesting something similar one of the variations I have on my web site but with the sheets where I show the pad-eye:
Let me clarify the application of the double soft shackle. The idea is that you have a jib out on a pole and a single sheet on the clew. You want to take the pole off, add a second sheet, and gybe. You are trying to attach a sheet to a sail that is already flying. You want to basically lasso the stopper knot that is attached (and stitched so it won't come off) to the clew. This needs to be a single hand exercise.
Another application is attaching a foot line to the tack. Again, you want something very fast. Because the shackle and eye are not bent, they do not have to be adjusted or milked around any curves.
These double soft shackles are very fast to attach. Faster than a standard stainless shackle. You cannot say that about anything you have to thread through the clew and put over the stopper knot.
Allen