Save your ink, soon somebody will be along to tell you your head would not have hit the ground if you did not have a helmet on.
I am with you on this one, as I feel a helmet may have saved my head from further injury more than once.
Or the opposite.
RoSPA clearly advises reference the THudguard:
.. should make a valuable contribution to risk reduction in a similar way to cycle helmets...
David W. Jenkins BA MPhil(Eng) PhD DCA FTSI
Product Safety Adviser to RoSPA
... and of course there is the testimony from Holly Willoughby how it would have prevented injury to her daughter.
So equally weighted evidence for Thudguards.... who will be buying one for their kids?