Cored hulls are stronger, being a "sandwich", but only to a point. I personally prefer a solid hull (at minimum below the waterline) and a cored deck, with the coring being Airex or some equivalent non-spongy material. I also believe that ALL deck gear should go through solid glassed-in pads, not only to distribute the load, but to discourage ANY kind of water intrusion. Here in Toronto, we have hordes of balsa-cored decks and the freeze-thaw cycles imposed by hauling out and storing boats in yards is horrendous. Very few escape nasty, expensive "recorings".
I know that for all the advantages of cored hulls (and they are many), I wouldn't want one if I grounded the hull on coral or something sharp. Not all of us can afford Kevlar outer skins.