Overlay is ineffective on white or black backgrounds. Luminosity makes black and white backgrounds appear identical. I would love to see a layer opacity called Texture that acts like multiply/screen layer. Currently, I take the overlay I want to use and divide it into two layers, one multiply, and one screen. I adjust the curves so that the screen layer is shifted to a darker tint, and the multiply is shifted to a lighter tint, and then group them together for my "Texture" layer. Then white receives only shades, black receives only highlights, and everything in between looks great. But it would be nice if there was a layer opacity that did that on it's own.