What does that mean? The full birth year? Are you saying 1/1? It's been discussed a million times and the January - March parents love it and the October, November, December parents detest it. The only date which will satisfy the age argument is the actual birth date where a kid moves up the day of their birthday. The kid is the youngest and progresses to the oldest. Then the January parents detest it because little Tommy goes from probably the biggest and fastest to probably on the slower and smaller side. It's never ending.
Sure the Jan kids have and advantage. But that advantage is limited to a 1-year age difference. Instead of the (2 year+) difference we are currently seeing in club lacrosse when it is split by grade.