I was asked about this asset. Simple answer is yes, it works as expected, but it takes a bit of know how to set it up. I will describe the process below.
I was using NeoFur 2.1 for this test. I will provide short list of steps, but recommend to read in full to understand.
1) Assign Fur Material as additional material on Mesh Renderer.
2) Configure Fur Material before pressing play (Select where to use Textures and where - single color)
3) In Playtime Painter disable Auto Select Material, select Fur Material and the Texture you want to edit.
4) Go for it)
Now in detail:
Without understanding of how materials, sub meshes and both assets work it's easy to get confused with painting Fur.
NeoFur needs each object to have it's own material, but to save you some time you provide one material and it will clone it for every object. Playtime Painter can edit a texture, but to save you some time it lets you selected a material and textures to edit. Problem is, Fur Material is not attached to object's Mesh Renderer, so Painter can't just get it automatically. You could assign Fur Material to the Mesh Renderer and then Painter will let you select and edit those textures. But keep in mind that the Material you assigned to NeoFur script will be cloned, so any changes to original instance of Fur Material (that is assigned to NeoFur, and now to Renderer) during play will not change how fur looks, because Fur is Rendered with a Clone of that Material. So you need to configure it before pressing play:
After selecting where we to use a single color, and where to use a texture, clones of the material will use the same textures, and in Playtime Editor you can select them and edit.
But the reason fur is not assigned to the object's Mesh Renderer by default is because Fur does not just change one shader for another, you still have your object, with it's original "skin" shader and Material, and fur is rendered on top of it. To be able to see your "skin" material and edit Fur at the same time, don't replace object's "skin" Material. Add Fur material as another material on your Mesh Renderer:
Unity let's you use many materials for meshes that are made of sub meshes. There is nothing complex about sub meshes, they are just a bunch of meshed stored as one, for usability. And if you have 5 sub meshes and 5 materials, each sub mesh will be rendered with it's own material. Again, it's almost the same as having 5 meshes each with different material stored under same parent GameObject. There may be more to it, I just haven't encountered any nuances to be mindful of, yet.
Now, again, to save you some time, Playtime Painter automatically finds the submesh you are painting on and selects it's material. And if you select Fur Material, it will select skin Material. So disable that Auto Select Material under material selector
Because Painter is not accessing Material that is actually used to render Fur, switching to Render Texture mode will not work: you can use it to edit texture, but changes will not show until you return to Texture2D mode.
The solution is not perfect because as Warning Message above says, it will cause additional Draw Calls.
So I'll contact the developer, maybe he'll offer a nice solution. Alternatively, in addition to NonMaterialTexture class I could create NonMeshRendererMaterial class for this kind of cases.