I also like the lightness and the snap of the stiff core, but they definitely land harder than foam core boards, and they ding easily, as Bonnie pointed out. The hard landings probably would not be a problem unless you are going huge and landing flat all the time, or unless you're an old timer with bad knees like me. The honeycomb decks also might or might not chatter a bit more on rough water, depending on the other characteristics of the board design.
Surflover, either core material should be fine for your kid. Just check the edges on an older used board to make sure there are no places where the layers are splitting apart, even a little bit, as this will allow water top be drawn into the core and ruin the board over time (delamination). good luck