Speaking of measurements. I think one of the most pertinent yet often absent metrics is distortion. And not just THD, but also the profile of the individual harmonics. Other than those who use the Klippel (Erin’s Audio Corner for example), I don’t see such measurements.
I think B&W 800 series might make for a good case study. Despite their non-textbook frequency response, I don’t find them nearly as fatiguing as other brands with similar responses. I suspect that’s because their drivers are low in distortion, especially offensive higher order harmonics.