Updated: Thanks for the clarification, fenderf4i. I had already written this before reading it, so I'll leave it as-is since some of it still seems relevant. So seems that "driver changes" I refer to = stators.
Well, even without clarifications from Audeze, this discussions seems to indicate that there is more going on than just the Fazor addition...
I wouldn't be too surprised, I remember when the LCD-3 was released (and I checked the specs before eventually buying one), the LCD-2 had a lower sensitivity on their spec page (~91-92 dB IIRC) When I looked at all this yesterday, I noticed that the current model now has the same 94 dB sensitivity as the LCD-3... so maybe also using the same driver but with different voicing? Quite possible in light of the different versions Head-Fi'ers compare in the LCD-2 thread.
It would make sense for Audeze from a production point of view, it's not that large a volume, and producing different drivers requires different fabrication tools or at least setups. So it seems they may have phased out the pre-Lotus drivers used in the LCD-2s in favor of the Lotus ones introduced with the LCD-3, and now they are phasing that one out for the current drivers introduced with the LCD-X/C... it's just more obvious due to the Fazors. They may even use the different diaphragms as advertised, but the driver setup using them has changed? But it's obviously hard to visually check, who would want to risk damage by opening the metal framework holding it...
This is obviously just speculation on my behalf, but I don't think it's unreasonable. And it certainly makes it very unlikely for me to send in my LCD-3 for an update since I really like it the way it is, esp. with my WA22, and I'm not entirely sure *I* would consider the changes an actual across-the-board *improvement* (i.e. not just sounding *different*).
That's really the crux of -to mod or not- in general: most people seems to simply assume updates (often at an extra cost) are always positive but why? What if thing are different in negative way? And in the case of this driver mod, it's not something you can press an undo button and have it like it was before... And then there's also the chance of damage or loss during shipping either way.