"Gerr" jib downhaul... any experience?

I came across a design for a jib downhaul on the web at:
http://www.widgetsailor.com/myboat/downhaul/index.html
Has anybody tried this and what were your impressions?
Thanks
http://www.widgetsailor.com/myboat/downhaul/index.html
Has anybody tried this and what were your impressions?
Thanks