I listened to both, briefly, on HeadphoneAddict's ZDT.
Impression from Augest (the HE6 was a leather-covered prototype)
[size=medium]*HE6 vs. LCD2 (both on ZDT): [/size]
[size=medium]-- LCD2 is brighter and more upfront. much narrower stage. I still felt a “tendency” of voice abrasiveness, though nowhere near that “grainy” impression I got when I was in Seattle. [/size]
[size=medium]-- HE6 has a more relaxed sound and is fuller, more realistic. [/size]
[size=medium]-- Still couldn’t handle the LCD2’s clamping pressure; The HE6 on the other hand is very comfy, did not feel too heavy either.[/size]
[size=medium]-- I don't like the HE6's leather skin at all. Meanwhile the LCD2 looks great. [/size]
[size=medium]-- over all, HE6 gets my vote, especially for long sessions. YMMV. [/size]