I have material setup where I’m blending two textures using vertex colors. The way it is setup, shows the secondary (blended) texture first, because by default Vertex Color is white (setting it up other way around is not really possible, because of how blending with heightmap works)
It would be cool, if we had an checkbox that change vertex color to black in those editors. It would allow to preview both textures, without placing mesh in level and filling it with color using MeshPaint.