The LCD-X is brighter sounding than the 2F or 3F but it's nothing like the HD-800. The 800 rolls off the low bass and has a big noticeable spike at 6-8 kHz. And I mean BIG - around 6-8 kHz is elevated from +6 to +9 dB from the midrange depending on how you compare it. Having a big response spike right in a frequency range the human ear is very sensitive is a huge flaw for any transducer that is supposed to be "high fidelity". Its sound is not the real thing, but a caricature of it.
The HD-800 is super-detailed, but to my ears it's artificial detail created by a uneven response. Its voicing of natural sounds is not at all realistic. I understand why professional engineers like its analytical sound to amplify every little detail in the music. But it sounds so unnatural and fatiguing there's no way I could ever enjoy music on it. It's also a harder load for an amp to drive with impedance & phase changing significantly across the frequency range. That's typical of any conventional driver.
It's true that you can hear the difference between amps more on the 800 than the X. Some people say this means the 800 is more revealing. But that's not necessarily true. Amps sound more different simply because the 800 is a harder load to drive, some amps are not up to snuff, so they have more distortion driving the 800 than they do with an easier load like the X. So the difference you're hearing is more distortion on the 800 coming from some amps, not higher resolution or detail.
In comparison, the X is is about as close to perfectly neutral as I've ever heard or seen in a headphone. The X does favor high frequencies, but it's just a subtle amount, perhaps 1-2 dB and broadly spread across the entire HF range, so it sounds very natural and doesn't impair realistic voicing of natural sounds. Also the Audeze and other orthos are very easy to drive, a purely resistive load with the same impedance & phase across the entire frequency range. So you'll have more choices for amps to drive it and get the best sound from whatever amp you pick.
To my ears, the LCD-X has all the detail of the HD-800, but it doesn't jump out and grab out. You have to listen for it. But that's what makes it so natural sounding - that's what sounds in the real world actually sound like.