Lever based downhauls have been tried on several different classes of cats over the years and to my knowledge, they have all been discarded. It would seem that the need to obtain adequate advantage from the lever system requires that the lever has to be "very long" or there has to be a multiple "pulley" system attached to it to obtain the needed amount of leverage. This has meant that either the "area" that the lever protrudes is very inconvenient (sheets get caught on it, etc) and/or, why have two systems together when one (a pulley system alone) will do the job of the two. There has also been "magic boxes" - where the pulley system is enclosed within a square or rectangular aluminium tube that is attached to the mast (or boom) and keeps every thing very "clean" BUT there has never been enough travel in the "magic boxes" for them to ever become "popular".