I haven't heard HD700, but condemnation from the community is pretty universal.
I would rather step down to the 500 series than use the 700.
Most people generally only reference the 600/650/800 when talking about high end sennheisers for a reason.
Oh, I love my HD800 SD. I'm referring to the HD700, which makes me angry thinking about. I honestly believe that anybody who likes the HD700 is just being difficult and stubborn, and there are plenty of those folks in this hobby.
I get it that many don't like the HD-700 but it also has to do with an individuals hearing, gear used, and also music choices. Many would not like the HD-800 on a bright SS amp and consider them thin, lacking bass and with a nasty spike, I've had a few guest over that like the HD-700 much better than the HD-800 due to the fuller sound with genres that need to have that full sound but if I were to let them listen to well recorded classical then they like the HD-800 or T1 better, even had a one person that thought the SR-009 was crap, but then the music that the person liked was pop, kpop and classic rock, it really depends on ones experiences, hearing and preferences when it come to music.
Another thing I noticed is many go to great pains to find an amp that pairs well with the HD-800 but you don't see this with the HD-700, many just use what they have then blame the headphone. I own both the HD-700 and 800 and also the HD-650, I've sold the HD-600 because to me they were the ones with a irritating peak which is different from the HD-700 and HD-800. Give the HD-700 a decent tube amp and it will reward you with a sound signature that I think is better than the HD-800 for some genres of music.
I also have a quite a few Grado's like RS2e, SR-225e, SR-225i woody, SR-60i woody, SennGrado, ypsilon and nhoord driver builds. The ypsilon makes the HD-800 a rather poor sounding headphone to those that come from the common Beats & Bose crowd. They are also a better HD-650/600, Ether/Ether C, and LCD-2/3 to a few others that have heard them and they are easy to drive, output from computer headphone jack will drive them without issues. Try an HD-800 out of a smart phone and compare it to the ypsilon and most will think the HD-800 sucks (as my GF put it) out of her iPhone.
Anyway, sorry for the rant, back to the HD-800
Another thing is once someone like Tyll or other well known reviewer a headphone tends to get a bad rep and many just paraphrase what they read without trying, not saying none of you never had a listen. And in a way I'd like to thank all those who say the HD-700 is not a good sounding headphone, it has driven the price down so much, IMO its a great bargain these days.