John:
My caveat about galvanized was based in the experience of friends back in Atlanta. They had a minor leak they ignored - after all, the pan was preventing damage, right? But the pan was sitting on a basement floor that was itself damp, and a hole developed. There wasn't a warning that the pan was holed, because the leak was small enough that the water remained under the pan; you didn't see it.
Came the inevitable day that a big leak came, and the pan allowed water to go a lot of places it didn't need to.
So, there's that. I will say that it took years, and that it took the kind of damp concrete floor you often find in the Atlanta area.
