I am curious too
Painter is mostly done for laying out a good color base, blending and adding some good textures into the paint.
Mostly after that details and fine tuning is done with Photoshop (I still think Photoshop is more precise for such stuff).
Painter def. takes some time to getting used to, but when you find it's strong side you will not live without it.
But I don't have a 100% working way of doing things, I just swith forth and back between the programs and sometimes it works other times it doesnt, but you can't beat Painter for blending and general paint texture.