I own one,, and would NEVER consider using it,, its purely nostalgia,, back in the early 70s,, I flew with one,, it was "maintained well" ,, was new,, and I had it fail on me,, ended up with the plane hitting a tree that used to be outside the circle,, but when the lines slipped it wasnt anymore,,
we are talking a contest,, safety of spectators,, personal property,, and the judges is at stake,,
why on earth would you risk that just to be stubborn,, there is NO advantage to a Ureely,, rolling up the lines on a conventional spool is just as fast,, and it also allows you the opurtunity to inspect the lines,,