Well that depends on what standards event organisers choose to implement. So far (as I'm aware) the Tay is the only UK event to date that requires a helemet, and they have chosen to go down the MSA Blue book route, ie the same specs as required for comp safari, which some might argue is overkill for a challenge event. Will be interesting to see if the MSA insist on blue book spec helmets for their new challenge permits. If not then even events run under MSA permit could implement their own minimum standard of helmet, all the helmets sold for the above mentioned sports do have to meet certain standards.