I think it comes down to what you feel is fair. If you think a 24 months gap is fair for a divsion of play or do you think it should be 12 month of a gap in age is a fair divsion? I know it ok when a team of mostly 9th and 10th graders plays a team of mostly 12th grades no one has a issue with it. But when we have teams with all 9th graders playing 8th graders we all go nutts. What about 7th graders playing 6th graders. Its all about each persons line and how big there kid is. And that is where it really all falls down to. If there kid is big for his age those parents are fine with it. But if you have a smaller/avg. size kid you want the 12 month window.