Reading reviews of the HD700 and I don't really know what to expect from these; some people say it's dark and not harsh at all and others say it is bright. There's a lot of polarizing opinions.
Well I live in a part of the world (Caribbean) where I import virtually all my electronics without opportunities to test (listen) them out. Like you I read a lot of reviews about HD700 before buying. I quickly ruled out HD600. Yeah, call me shallow, I accept, it just look so ugly (at best plain and cheap looking) to me to even consider it no matter how good people may rave about it. Same reason I will never buy a Chord Mojo (not cheap looking just ugly egonomics), but that's a different story. So I read reviews for weeks on Oppo, HD700, HD650 and many more. And like you noted so many varied reviews. What did it for me were:
1. Far many more positive reviews than negatives
2. Extremely comfortable to wear (appears to be universal agreement on that)
3. I find it a beauty, futuristic, molded like it's big brother HD800s
So, off to importing, waiting and paying customs duty.
I have had it for more than 6 months and I can say without hesitation, HD700 is one of my best buys in recent times. I listen to all kinds of genre; Blues, Rock, Classical, Hip-Hop/Rap, Pop, New Age, Electronic, Dance, Reggae, Jazz and never have I found it lacking. As for the high sibilant, don't know, I guess I don't know what it means because except for one or two occasions I've never really felt it, so I chalk it down to a bad recording.
My desktop dac is Fostex HP-A4 and mobile rig is a stack of Samsung J5 phone + Fiio e12 amplifier. Even with that low level mobile rig, it sounds really good. I just ordered the new Sony PHA-2A waiting to take ownership next week to replace the e12 and I'm expecting my HD700 to even whoa me more. Ultimately planning to replace the Samsung phone with Sony ZX2.
I've worn the HD700 for 6 hours straight on without even noticing I had it on. My HP before this was Hifiman He-400S.
These are just my thoughts on this wonderful Headphone.
Just a note, mobile for me is not wearing HD700 in pubic. It means I take it to the office with me along with my mobile rig. Not really suitable for public as it's open back and if you work in an "open" office not a good idea either.