Hi torsten, things that are kind of puffy or semi-blobby looking can often be more difficult to model in NURBS because they usually can't be done only by using 2D profile curves.

But usually with transitions you will be looking at fillets or blends to do the transition area. Fillets tend to have problems when they sort of evaporate to a single crown point like you've got here, so probably putting in blends for those areas might work better.

- Michael