I had planned to do our locker floors myself, but my better half convinced me I had better things to do (smart girl!) I was even more appreciative of her advice when watching the guy who did the work climb out of the locker covered with dust after grinding in prep for the lamination work.
Our plywood floors were replaced by foam core, with glass laminate on both sides. It will last the life of the hull with never another issue.
We also added permanent limber holes in the floor of the lockers. I tried really, really hard to think of a good reason to hold water in the lockers and not let it drain to the bilge and I could not come up with a reason why water should pool there and not be pumped overboard.
North Bimini, Bahamas