IMO it's worth the extra to get the LCD2 Rev 2s. While I love the HE-500s, they fall behind in a majority of musical genres, particularly jazz and synth (my two favorites). I'll still pick them for classical, but most times I just plain miss the lush, natural mids and endless, effortless bass of the Audeze LCD2s.
Yes, for me, the HE500s are preferable to all of these. They are simply musical and non-fatiguing, have great deep solid bass, have ambience, have more than decent detail, and are just plain natural and I
choose them often for my listening sessions and just don't want to take them off.
(Note: I especially like my Moon Audio Silver Dragon cable with them.)
I just yesterday found Tyll's Innerfidelity video review of the Hifiman phones and he seems to have come to the same conclusion that I have.
FWIW, Tyll also prefers the LCD2s to the HE-500s, even the Rev 1s.