Upper mids and vocals are impacted when compared to other headphones. If you value vocals, these will not be your first option. For Soundtrack music, these excel, for example.
I agree with Andrew regarding the LCD-X,the GLs are great but could be considered as a side grade and a different presentation of sound at that level. The HEDDphones are fast and more visceral with great vocal presentation for metal. Diana V2s are also more detailed, smoother and coherent. They also have better controlled and textured low-end. Finally, the SR1As, Abyss 1266 TCs and Utopia are a cooompleeeeetly different league... Leagues even, but it isn't a fair comparision given the price points.

All in all, excellent value and remarkable build quality.
What do you mean when you say that the GL2000's mids are " impacted"..
You can say that about every set of headphones, as compared to every other set.
So, that's kinda moot = utterly vague.
I could say that all the Abyss gear has a impacted treble as compared to the Senn HD600, and in fact that is a fact....but, does that mean the Abyss Treble is not great?
Next...
The LCK GX are not a primes sound, if we are discussing summit fi., so, if you think it is, i'll have to give you a psss on your evaluation of the GL2000, no offense intended.
As, If we are comparing the LCD-GX to gaming sets, then, they are very fine, but as true audiophile gear, they dont really compete with anything that costs $1000.
They are woody, dull, soft sounding, mid-toned, and the bass is reserved and strange.
They are trying to be flat and neutral, and that is what you get.
Abyss Diana2, have too much bass, but are quite detailed, and in fact, very lean sounding....
If you compared them to the Rosson Rad-O, for example, you would think you were listening to nothing but treble.
So, im not sure if what you are listing as your comparisons, are world class audiophile sound..., but as lot of people like microscopes on their ears and believe this is "audiophile sound" then ,those you listed, do that well, except for the GX, which does not.
And the Abyss 1266.... that's an odd tho beautiful bird, as its not a musical sounding gear, but its not designed to sound musical, its designed to sound like microscopic details on steroids.
I like that, but, its not something that you want to hear for hours...
Ok then, i'll get the GL's soon, and then i'll let the reader's here know if they should put them on the short list.
thanks a lot.