I'm also vote for LCD-2 rev.2 for rock and pop music. I've bought them after Senn's 650 and it was revelation... Much more sound's resolution, music plays easily and detailed. Same time it is not harsh and tired trebles, it can be listened on high volume without tired.
But now I'm also look on a HD800 for insatrumental music (but unfortunately never listen them before).
At least I know, for most the high resolution recordings I downloaded form HDtracks, mostly female vocal and orchestra, nothing comes close to the HD800. The image and sound stage puts you right in the scene that makes you forget you are actually wearing the headphones.
I tried AB it with LCD2, and found while LCD2 do have batter in the bass, HD800 beat it on every other aspect. It is not that LCD2 is not detailed enough. It does has all the detailed present, but due to the slightly narrower sound stage, it makes those details harder for me to pick up. As for HD800, since everything is separate widely, every single instrument has been present at its own place effortlessly.