Yeah I mean there's a lot of factors at play and in the end it's the owners of the headphone that have to decide the priority, as I've said numerous times my approach is that there's no right or wrong as long as all the factors and measurements are being taken into consideration for the final tuning. For me I'd rather have low distortion, better transient response, impulse and CSD's rather than give those up just for FR. I personally find it more pleasing and many of our owners do as well.
Here's a recently measured THD of a headphone on this site that does measure to harman:
View attachment 331783
Here's the Caldera from page 1 of this thread:
View attachment 331784
Now the question for the potential owner who absolutely has to have Harman tuning for their particular HRTF (which as you know I don't always but sometimes ascribe to based on the headphone format) is whether they should EQ the headphone with the better THD measurement or take the other stock tuning? There's no right or wrong for them as long as they are happy right? BUT, various users will have a greater chance of hearing distortion and how it manifests in the headphone with higher THD, and also potentially have to deal with worse impulse response and other variables in the headphone that gave up those areas for the cost of adhering to harman target.
Again, no absolute argument on what is right here, as you know ZMF makes options that are closer and further to harman - BUT - just that there isn't a clean way to get to harman without sacrifice in some situations and we as manufacturers have to make individual choices for what we feel is best, just like the owners who utilize our headphones. It's a good thing there's a lot of great choices these days!