I also understood the question. I can understand how the fazor helped clean up and improve the imaging and as a result it changed the sound. Now, same people may or may not like this new sound as it comes down to preference. However, what I (and perhaps others) was wondering about was if there were any tradeoffs with the Fazor technologically. Was it all beneficial from a purely acoustical perspective? You fix the diffraction with the Fazors, but do you create another problem? Again, I'm not talking about preferences of listeners, just from a measurable standpoint.
For example, since I came to this forum, I've always heard of the Sennheiser 6k peak. During my time of Audeze ownership, I've never heard of treble peaks until now. Some may say have said dull or laid back, occasionally bright, but never any mention of peaks or non-coherent treble. I've been reading and going back to see how people liked/disliked the various introductions of Fazor. Lots of comments started popping about the peaks or uncoherent treble.
Now, it may very well be the case that this cleaning up by the Fazor just makes them more revealing and highlights the problems in the recording better which were previously buried in the non-fazor versions. In which case, props to Audeze, for giving us the option to choose between the two models. Although, if there some other tradeoffs happening acoustically because of the Fazor, then wouldn't that be something. All speculation on my end. I cannot even confirm this subjectively as I have yet to hear a Fazor.
Towards the industry in general:
With the 2C, I'd rather take a somewhat dull sound than something with peaks. The HD 800 got annoying when I was constantly switching between my monitors and other headphones. Nothing makes me put a headphone down faster than treble peaks. In fact, I have Sonarworks and for fun the other day I went through a bunch of headphone profiles at 100% calibration. So many bright headphones. The industry needs to stop with making headphones so unnaturally bright just to make it appear detailed. Perhaps, it works for beginners and tricks them into thinking something is more detailed. However, for high-end users who've had experience and aren't fooled easily, I see no reason why new top headphones are still bright.