Not me. I still don't have a way to determine if my step wedge is neutral. If it is not neutral then I have no way to compare, to within the proverbial gnat's behind, what I measure with what you measure. I know that some of my negs are not neutral, but neither of us will know by how much from either my measurements or yours, even if we use the same filter, unless we know the native spectral sensitivities of our densitometers as well as the transmission spectrum of our filters.
It is true that when we are dealing with negatives that look neutral we can get a mutually agreeable measurement of contrast index, so that if I tell you that a certain film-developer combination developed under certain conditions gives a certain contrast index, you ought to come within experimental error of the same result in your darkroom. It is also true that what difference there is will be most likely in the form of a difference in film speed rather than in slope if it is due to, say, the difference between a CdS photoresistor and a silicon phototransistor.
I think we stand a better chance of comparing certain results if we stick to narrow band filters. The color separation filters may be narrow enough for most purposes, and a UV bandpass filter for the rest. Determinations of film speed by densitometer readings are subject to validation by practical use.
I'm not trying to pontificate here, just bouncing thoughts off the backboard.