Unless I misunderstood what you are trying to say, isn’t it already something we can do (and do) with ACES? It is a scenario that was deemed highly non-desirable. The inverse + forward approach is subject to many issues WRT precision, e.g. quantization, especially with a LUT implementation, and performance, i.e. double-transformation cost. From an architecture standpoint, @daniele’s proposal here, inscribed in the “put-your-own-DRT” paradigm, is much cleaner.
Cool stuff! Quick question though as I haven’t loaded your Nuke scripts: What is the Y-axis red line here? Might be worth plotting 0 on the X-axis also.