When I tryed one, it slowed my arrows down by 20fps. With all the worry about fast bows, it kinda defeats the purpose of getting a decently fast bow. I like to shoot at least around 250fps.
With all due respect , if you lost 20fps you have some tuning and/or spine issues! I' ve setup countless whisker biscuits in the last 3 years with a maximum speed loss of 5fps and that was with 5" vanes. The normal speed loss is around 2-3 fps.