While doing the OkishDRT I wanted to use the same tonescale as the ACES2 candidates use, the Michaelis-Menten Spring Dual-Contrast and needed its derivative to drive the path-to-white. It turns out there is a sudden transition in 0.18 where the tonescale changes from the linear extension to the michaelis-menten function, as seen in the following desmos plot: ACES2 MM-SDC tonecurve. Not sure if this is a problem for the tonescale but for using the derivative to do things it probably would be better if it was smooth.