Really into mainstream music and pop, as well as opera sometimes. When I put on UE700 (+Cowon D2) - the sound signature was detailed, initially rather harsh, almost tiny, not 'bright' as some implied. With a bit burn-in, became more tolerable. From memory, had above average soundstage, something it really outpace RE0 in. It has the 80s tone to the sound, great if you're into rock. Quick, sharp attack, yet without prolonged bass to supplement the stage. Being a bass head, the lack in bass presence rendered it poorly choice for me, even my Metro 170 felt more suitable for my taste. Don't get me wrong, while it had decent, but not exceptional mid nor low, the high really sparked with right tracks. The reason, I say that, is sometimes, for few tracks, such as 'Boulevard of broken dream', it simply smashed them with stunning amount of detail, reproduced the music in a way I never experienced. When the wrong track plays, it sounds harsh. Had Metro 170 before, matching my taste almost perfectly for about, setting me back merely £10, yet producing impressive bass. When I got UE700, had unrealistic expection - later on it became apparent UE700 was more satificatory for narrow selection of tracks. For most tracks it leaves something to be desired. While certainly an upgrade, was largely unqualified success imo.Playing 'Long Shot' by Kelly Clarkson, starts off to great start - but then there was the absence of distinct vocal, as well as low. - not quite meeting my expectation for $100/£70. Overall it it a good set, only worth about $100 though. My feeling was it was not as refined for a wide variety of gene - though with relatively natural, if not a bit bright sound and UE high, as well surprisingly compact body, gives makes it great set for budget UE lovers. Music aside, I must give kudos, that Logitech would beat Head-Direct any day in support, speed. As a benefit from merger with Logitech, the new lineup of UE really has been mainstreamed; its cable is an example. With RE0, there were alot of microphonic noise - UE700's cable eliminated it elegently. Offering almost comparable quality to previous flagship, while delivering quality, and far more user friendly products (UE700 is TINY physically), at a fraction of the cost.
My recollection of RE0, was that it had cheap $10 headphone set build quality, larger physically, and didn't fit as well. Honestly if you didn't hear it, you wouldn't think they cost so much. It did have extreme natural sound. Music wise, even with different tips, and after the bass mod, lacked real punch. Overall I'd say it had rather flat output; paired with D2, it should made a dream combo for audio purist - though I personally resented the sound signature. Like UE700, it lacked bass presence, marginally more this time; the mid similarly felt slight further recessed - and the high, while is rated highly by others here, and is very impressive in itself, didn't rival UE700 - in addition RE0 felt let down by the absence of any sort of soundtrack. In signature from what I could say, these two are very similar in weakness - UE700 overall edges out with wide margin. My RE0 broke within weeks with one speaker not working. Not for me.
Either way, make sure try it first. For you, I think UE700 does better. They are equally fast, in complicated scene RE0 sounds muddy, as it lacks decent instrument separation, which can't be blamed as UE700 has dual drivers.