ken, can you point me at some such references?
i guess part of it does depend on what type of flail you are running.
our local occupational health & safety literature indicates a fair risk of injury with a flail especially if proper guarding on machines is not used. one example is a guy using a flail on a tractor, the flail was arm mounted and offset and he had the tractor door open for whatever reason. the mower flicked a piece of wire at him which pierced his heart.
the rotary type mower may throw things just as hard but the direction of throw is horizontal.
don't get me wrong, i'm very curious bout flails but my research leads me to concur with what i originally posted in this thread.
further thoughts?