Customization indeed wins, sir! I like the "we'll use dungeon tiles for the delve" idea.While I am not knowledgeable about the exact numbers, I am pretty confident our Dungeon Tiles vastly outsells any map product we've produced. While maps are easier to use, they are harder to customize. With mapping, customization often wins, I think.
Does wotc plan to reprint any of the "DU1, DU2, etc" dungeon tiles? It looks like halls of the giant kings is already out of print.