Filmic vs Sigmoid - when to use which

Let’s stick to grayscale and floating point, as used by dt.
Middle gray (for filmic as default) is at a grayscale value of 0.1845 (no logs or exponentials, please). This is declared to be at 0EV.

Just do a short search for “middle gray darktable” in a search engine.At least one other thread discusses this.