I wear a size 43 in the Dansko professional clog.  I have tried on some of the "girlier" Dansko styles in size 42 and they have been too small, so I was delighted to see that the Stacie is made in 43.  However, the 43 is too big for me, and the 42 fits.  European sizing can be confusing for Americans (because it's circumference and not length), so if you are in the US size 11.5 range, go with the 42 as recommended, even if you wear a different size in other Dansko styles.