Playing up is fine so long as you know what you have signed up for. The problem is that with no age restrictions you cannot make an informed decision. I made the mistake of allowing my son to play up (6th grade playing on a 7th grade team) only to find at a tournament this fall that his team was playing an 8th grade team with a number of hold backs. The situation in my judgment was dangerous and the result was predictable.

It was ultimately my fault, but it was really infuriating.