I jump 1.15 to 1. In a canopy class I was strongly urged to collapse my slider, pull it down, and loosen the chest strap. I had always collapsed it and just left it up there, thinking no reason to pull it down.
The second I loosened the chest strap a few inches the canopy changed it's glide slope so much that it felt like I raised my brakes a few inches if not more. My heart missed a beat, I was not expecting something so drastic. Now I always do it (after I am 100% sure I have time, sometimes I am flying in traffic the whole way down and have to live with a flapping slider up there) because my canopy does fly and land better, just as my canopy instructor promised. And, that is at low wingloading. Out of curiosity, and apologies for the continued hijack, must the slider be collapsed to gain the improved performance you noted when the chest strap was loosened? Have you evaluated the effect of just loosening the chest strap?