After a few hours more listening I've completed my audition and comparison of this 2016 LCD-2 to my 2014 Fazor. I confirmed my first impressions reported earlier and given comments here [thanks for the tips], really focused on midrange. The 2016 midrange voicing is more ethereal. The 2014 portrays the woody core of cello, the midrange resonance of piano and human voice, with more presence than the 2016. And I like that presence. It's hard to say whether it's more natural or realistic because the amount of presence one hears in reality depends on the size & shape of the room and where you are relative to the musicians. It's like the edge of sound a violin makes when it's being played 3 feet from your ear. You never hear that in the audience, not even in the first row.
However, the 2014's midrange presence becomes a slight glare that veils complex or large ensemble music. With choruses, symphonies, etc. the 2016 is glare-free, resolving individual instruments and voices more naturally and clearly. Combined with its faster transients and tighter (yet not louder) bass, it's a great sound.
So the 2014's mids have slightly better voicing, yet it comes at a price. The 2014 over-emphasizes mid presence, the 2016 under-emphasizes it. I think the 2014 is a bit closer to reality. By comparison, the HD-600 emphasizes it far more than either, sounding brassy in comparison.
Overall the 2016 is better in many ways, but not in every way. I'm definitely keeping both. Still haven't decided whether to upgrade my 2014.
PS these 2016s are dated June 28. I asked Audeze whether they made LCD-2 driver changes since then, will post their reply.