I have a decent understanding of the rule. What I'd like to hear are some reasons that you use it over a straight nine beyond the 'free' substitution it gives you. Any player specifics or game situations would be great to hear!
That's all I can see using I for on our 10U team. The skill spread isn't so large that it would be an advantage to split some kids as strictly offense or defense.If a tournament allows only DP/Flex, I will use it in pool play if I think it helps get more players into the game.