There is simply no downside to switching to an age based system in youth lax. The exceptional athlete that is currently on age, but enjoys competing against the older holdbacks can still be challenged by the older kids by choosing to play up (a 2007 can play with the 2006s).
As for the puberty argument, yes, on age kids who hit puberty early have an advantage, but this advantage is limited to physical ability. They are still age appropriate mentally, and this is a big part of the game. An age based system eliminates, though, the kids that are BOTH well into puberty and older. These are the kids who really don’t belong with the younger kids.
And when arguing for a change in a system of any kind, you do not have to prove that the new system is perfect. You just have to prove that it is better than the current system. Of course an age based system will have big and fast kids who hit puberty early. But it will have less of these kids, and hence will be better. And of course a January bday will have an advantage over a December bday, but this will be the maximum advantage seen. A grade based system with holdbacks often sees kids with a nearly 2 year advantage. The former will be better than the later
