One more thing...

I believe that all three toilets that you are considering use the Giberit tank carrier system.

I am not 100% certain about the Duravit Starck 3, but I know that the Stark II uses the Giberit carrier.

Check this out for more info-- just click on the "Spec Sheets" at the bottom of the page for a listing of which manufacturers use Gibeit:

http://www.us.geberit.com/us/Webus.nsf/pages/prod-toil-conce-1

Regards,
James