I actually happen to agree with Teflon. I learned a lot through doing staff pt 2 which was useful in assisting the squadron, and it formed a useful transition to staff.
I'm actually in favour of ending cadet service at 18, with a transition period of 2 years open to former cadets and members of the public where they are under training. At 20 they can apply for CI, SNCO or officer. During this time they are allowed to run activities with supervision from other staff, unless they hold an NGB qual in which case we defer to that.
They would be responsible in exactly the same way they are now, but the difference would be they are unequivocally adults and treated as such. They would, for all intents and purposes, be CIs for staying in the mess etc, and wouldn't be able to claim pay.
They would have the same access to courses that all staff have, but also the same access that 18+ cadets have now. Still a halfway house, but much clearer that they are "probationary staff" and not cadets.