An old customer sent me an e-mail regarding LCD-2 and HD800 as he is a T50RP and Magnum V4 driver currently.
Answer: HD800 Master Race
HD800 does a sweet treble, actual punchy bass, and the midrange was perfect before the HD800 left shelves, now that were on multiple driver revisions, it's basically like a Porsche 911 GT3 now. People like other stuff some of the time, but it's still something you want ALL of the time.
Downsides to HD800 Master Race:
Treble can be laserbeam-ey at times. Soundstage is somewhat artificial, the concept of soundstage with headphones is an illusion from driver angling and spacing. Wall of sound = you're not deflecting the full fury of your drivers in an attempt to IMAX your cans. Also their transparency wreaks havoc on wallets. LCD-2 could care less if I ran it off an RSA portable amp or a $1500 Schiit tower of power.
All of these statements were made running off an AudioGD NFB 10.32, 6 years of Head-Fi experience, and my own brand of cables.
All IMO of course, both are strong headphones, and you're probably in a good place if you own either.
You could just say screw it and go Mad Dog with a silver recable IMO. They're really that good even though I hate modded cans that aren't Grados.