I never really found them necessary for upwind/downwind course racing. For fun reaching, we use a sissy cord (http://www.hobiecat.com/forums/viewtopic.php?f=9&t=35385
). If it's really windy, the skipper sits right in front of or on the rear crossbar with crew straddling the skipper and the jib sheet in one hand and the sissy cord in the other. Probably safer from an ankle injury standpoint plus the crew isn't limited to one location. The F18 guys obviously use them though. I've personally never liked the idea of strapping my ankle to a 400lb boat - the boat goes one way, you go the other, the ankle loses.