@Glyph I've "used" my fangs twice. Once when accelerating to try to cross an intersection (so from a dead stop) and once when slowly going uphill. Prior to installing them, I experienced both a low speed, quick acceleration nose dive (mostly embarrassment and road rash) and a high speed (21 mph) nose dive where I don't think the fangs would've helped at all, nor do I want to find out (major road rash including the knuckles on my left hand, bruised hip, sore shoulder)! I now keep my speed at a max of around 15 mph to help prevent the second type. Both times I've engaged the fangs I got "oh no!" feeling that I know I would've been on the ground without them.
My riding is pretty much pavement and relatively smooth hard packed dirt, so no crazy trails or tricks where the fangs might get in the way.