What about mold forming under the tiles? Can anyone comment on that?

Our Diamon Grid-Loc Tiles are mold and mildew resistant. Mold and mildew can grow if there is organic material, but it would not grow under the tiles. The only thing that you might notice is if you have a water issue with your concrete, you may get some salt accumulation under your tiles. This can be easily cleaned and will not affect the tiles in any way.