To be honest I think the average holdback is hurt in the long run. Once in HS size and physicality evens out much more than in middle school and below. If you are not working hard as u can u are going backwards in the elite divisions of summer lax.
Pediatric studies show holdbacks are hurt in the long run-- but that is emotionally and mentally. Science proves those kids get dumbed down and underperform. Basically data shows most kids will adjust to their environment. For kids who skip a grade or are younger, they learn to accelerate and fit in. For holdbacks, they learn to do less well to fit in. BUT that is for academics, social adjustments, etc. For sports, they have physical advantages and kick [lacrosse] on younger kids through high school.
in other words, if you're willing to sacrifice your kid's well being in hopes of him playing lacrosse in college, that path is there.