the way I see it, having "flowing" hair does not necessarily mean that it is too grown. Growing up, all of my classmates had long "flowing" hair down their backs to their butts and none of them looked "grown". Granted, I did go to an all-white school. My point being that just because a little girl's hair is long does not automatically make it not age-appropriate. Now, highlights, or a big blowout, or layering is different.
Growing up, my mother didnt let me wear braids or a relaxer or anything for fear of me looking "grown". I hate her for it. She also had no clue how to care for ethnic hair either. So, growing up I just looked homeless and got tormented for it. All that being said, I would be real quick to grab the Just For Me. Hair grows back, and it certainly should never define you...or your child.