I've just tested this out (the file Converter). It seems to work fine for light weight 3ds files however, it had problems generating kml files from moderately complex geometry. (~900K 3ds files)
The UI is not much to look at; and having to type in coordinates manually is a pain. (It would be nice to import a placemark as a seed file).

The converter is $150, which is not offensive but still high for what feels like a beta product.