I bought a pack on clearance for cheap at Walmart with the hope to use them on turkeys. Never shot one since the folded blades were too wide to clear my riser. First time I drew my bow with one on, the blade hit the riser, popping the nock off and rattled to the ground; falling razor blades and no arrow on the string - always a great combo!
Beyond not being able to draw them, the collar mechanism appears like it would cause significant drag through an animal. The blades weren't very sharp either. Glad I only paid $15...but I guess I know why that was.