Early on, 2008, there were problems with the "facers" on the thicker panels made in Germany. Later, Schluter conducted a very thorough inventory/inspection of everything in stock and thought they had weeded all the defective panels out. Apparently, some of them slipped through. Corrections were made, and the problem was eliminated. There is no reason not to use Kerdi-board at this time It is a great product that is being used routinely by contractors I know. If you should run across a defective panel it will be replaced at no cost. There shouldn't be any more of it out there, though.
Once again, this has nothing to do with the steam room that is the subject of this thread.