RE: "Form" post.....never done this...
My experience with shooting off the string and shooting with a loop is sort of a combination of the two... I shot off the string for almost a decade or more, and only had to reserve once. My issues with it came in the fact that I was wearing out the eliminator buttons (the rubber cushion buttons to keep nock pinch at a minimum when shooting off the string). I found that them wearing even slightly would change my POI.