I found out something to be very informative. maybe it is obvious to most people but I never saw someone mentioning this.

don´t smooth skin with IK!


after joints and IK have been setup I bent the skin to the skeleton. and when it came to weight painting I got weird vertex movement all the time. one workaround could be fixing those verts in the component editor, but the artisan paint tool cracks it again.

so I left the IKs while binding the skin and painting weights is fine again.