Good review Magick, so should I go for the TH900 or the XC. I am looking for a slightly warm but not dark signature.

Either will fit that, they're both exceptional headphones. If you want a more neutral experience with better isolation (a lot better), the LCD-XCs are for you. If you want something lighter and don't mind a slightly "U"-shaped sound sig, then the TH900s fit the bill. Either is a great flagship product, but as reference closed cans, the choice is the LCD-XC.

Hey, is that a man with a woman's face or a woman with man hands, either way I'm out?

Just my 2 cents.

What about the AKG 812?

Looks like a woman, no idea though, it's just some image I found.

The AKG 812 is an open headphone design, not closed (aka. sealed). They won't have the LCD-XC's superior isolation, which is the main point in considering them in the first place. If you can get by with open cans, then there are more options available.

Ahhh Magick Man.... I was waiting for someone who I follow to review these, I do like my Th900's but they are not as fun as I tend to like my cans. They are great and I like the bass, I am a basshead for sure. You allude to the TH900's being U shaped, would you say that these are more V shaped or "flatter" than the Th900's? I have never even heard an Audeze product and really want to. I have to have closed back. Would you say it is worth me picking up a pair of these considering I am searching for an improvement on my 900's? I actually bought some 600's also, and prefer the bass on them, don't ask how or why, I just do. I am probably going to pull the trigger on these very soon, just wanted to know how the bass compares to the 900's. I see that you are not a fan of too much bass but like these, so maybe I will be disappointed. What do you think?

A woman with man's outfit ( this is my 1st Comment )

... HURRAY happy to hear these are on the neutral side! 
 
My w1000x [Very Modded at this point] needs an upgrade :/, I'm thinking this shall be the way to go :3, optimally I'd like to end up with a TH 900 and XC... as atm I'm the owner of a W1000x and WoodBack D2k :3 so I like my woodies... like em BASSY heavy and bass clean! 

gonna glue some exotic wood veneer to my LCD2...already spent my bonu$$ 

I'm not out to stymie anyone's enthusiasm, but these aren't "bassy", however the bass that is there is very accurate, fast, and deep. Low pipe organ notes will vibrate your cheekbones and make your ears tingle. For bass quality, I'd place them right behind the TH900s, but these are a more well-rounded headphone than the Fostex, and like I said in the article, they're at least an order of magnitude better at isolation.

How is the leakage? Are they like the Fostex/Denon headphones which at decent volumes they leak like a sieve? Thanks for the review!

No, not like the TH900s at all in that regard, they isolate both ways very well.

any heavy metal listening?

They're excellent with metal, their clear tone and extremely fast bass really come through.

Glad to hear that.  Thanks for the fast response.  Kudos to you.

These  do seem to be a great headphone. Hope to see a comparison of the X vs the XC some time.