Soft shackles are both strong and secure if made properly. The knot is about 6 diameters of rope in diameter that would have to be forced out of the 2-3 diameter opening. When loaded the hole is held closed and would have to have the load removed in order to open it. When a load is applied the hole or opening closes by itself so there is no danger of the rigger not setting it properly. The only down side I see is the pick ability of the Tenex. Also the style of shackle that Nick shows would take longer to attach because of the sleeve. Other types are just a loop that are easier.
I have used a soft shackle as a main connection point on one of my harnesses and had no problems.
I have used a soft shackle as a main connection point on one of my harnesses and had no problems.










