New and proud owner of a pair of these wonderful cans, and I have to say that the W1000x's really hit above their weight class so to speak, as someone who uses the LCD-2 and Heir 8.A on a regular basis, and has previously owned the HD650s for quite a long while (my first hi-fi cans) the W1000x's are really something special. Here's a short little comparison for you guys :)
There's just something about the way it renders 3D sound stages beautifully, better than the LCD-2 by a long shot in this regard. the imaging is perfect and very very surreal, if you enjoy live recordings this is a BIG plus. They have some amazing bass, doesn't reach as low as the LCD-2s or my 8As, but a very satisfying mid bass punch to it. The best thing about these have to be the amazing, smooth treble, that goes all the way up but doesn't seem to ever fatigue, makes for listening to female vocals particularly pleasing, better than the LCD-2 with female vocals, though the transparency is a bit of an issue with some albums, you can tell they're coming out of headphones, not really like the "out of nowhere" transparency of the LCD-2s. But still, better at female vocals, while the LCD-2 takes the cake with the timbre of male vocals, Michael Buble just isn't as amazing on my W1000x's as on the LCD-2s :)
Oh and comfort-wise their probably better for most people, though I'm one of the few freaks that find the LCD-2s comfy as all hell, but for most the lightweight W1000x make for more comfy listening sessions. The only big downside I guess would be the fact that it's not a particularly speedy or transparent phone, though I rarely listen to music that really makes the lack of transient response very apparent, though the transparency does irk me for a few minutes after swapping between my 8.As or LCD-2s to the W1000x's.
Compared to the HD650's, at least from my memory, was that the bass, mids, treble and soundstage were all more impressive on the W1000x's, and more comfy too :) I did have a crappier amp at the time and I'm sure with the scaling of the 650s on better gear maybe they'd sound better, but on a budget, without an amp and for about $350 on the market, the W1000x's would be my go to choice, no questions asked.
I think it's a bit hard to compare the W1000x's to my 8.As, given the nature of IEMs and headphones differ in so many ways, but I would say in all aspects but soundstage are the 8.As superior, but then again I find them to be my perfect sound, so... :P
Overall an amazing pair of phones, definitely better than the HD650's and competes heavily with my LCD-2s for head time, now they're by bedside listening headphones, and I'm loving them :) Hope this helps with anyone who's considering either the LCD-2 or 650 over the W1000x, cheers!