How about 3D in Ppainter?
what do you think about it?
Would be a good idea and could maybe get better painting results....most 3D programs have "paint in/on 3D model" but less sophiticated brushes. But how many painters paint 3D models? that need Painter brushes?
Alternatively you can paint 2D using Painter and apply the image as a texture/UV map onto a 3D model...just not as direct as painting directly onto a model.