The fazor evened out the sound signature, giving the treble more presence and clarity instead of having a bit of a mask over it. To some, the pre-fazor sounds better because they prefer how the bass was more center-stage, as it were, but personally I think the latest versions all sound better than the old stuff. More air, bigger soundstage (not HD800 big, obviously), just more coherent and even from top to bottom. The bass will sound the same, possibly a bit more responsive, but there will seem to be less of it since the high end is more responsive.
Comparing the 2 to the 3 is a little tricky. They're obviously brothers, with the 2 just sounding "smaller" than the 3 overall. It's not as big and full, not as clear, not as lush, but these are comparatives only, because the LCD-2 is still a marvelous headphone.