Gonna bump.
I'm a gamedev - primarily a texture/material artist. I use Substance Designer and Painter regularly which I both l love. That said there are some things that I think both pieces of software don't necessarily lend itself well to.
Currently I'm actually using afp for scan processing. Other than artomatix art engine (which might be good for inspiration as well) afp is the only other software I know of that would allow me to easily copy/clone multiple layers to create a tileable material.
That coupled with a simple 3d viewport window would go a long long way.