different opinion here, in LL I would say there is no advantage what so ever. it is bombs away from u10-u12. Let the boys enjoy it is supposed to be fun.
At 13 we trained with a BB core all winter and played a split season with BSER (or whatever the exact letters are) and BBcore. the minus 3 did what was needed for weight, strength etc. The sweet spot is what is, the object of every kid is to hit it square regardless of the material.
The fall of 14u he started playing some wood bat, by the fall of 15u it was almost exclusively wood bat. We actually have an advantage with wood now because he hits the sweet spot a higher % of times then 90% or more...but he never trained once with them until he was 14.
The other side of it is my younger one started training wood at 11 because his coach thought it was important...it wasn't he is no better or worse because of it. Now he claims he is better hitter with wood, we all know that is just silly but you can't convince a 14 year old of that!
Bottom line is if the boy can hit, trains well, uses a good approach to his AB's it doesn't make a damn bit of difference what he trains with at 10,12 or 14 IMO.
What matters is if he training properly so when they make the switch to wood it really isn't an issue.