Okay, I did a little comparison between the EX1000, GR07 and for fun, the FXD80 as well. It didn't really change my mind about all three, though I'm reminded again of why the GR07 is so great.
The EX1000 is the driest of all three because its spiked treble region gives everything a kind of dusky, slightly hazy sound - because of its emphasis of hiss it reminds me a little of the sound of an old tape (Of course, a much better sound then that, just a memory haunting the signature is all heh). Apart from that particularly characteristic it sounds quite neutral, but the treble can get splashy and sibilant on some tracks. The soundstage presentation is the best of all three to me, with a real feeling of 'out of head' - ness to it. Overall a beautiful and natural, though at times a little too dry, sound.
The GR07 is not as natural sounding as the EX1000, but is actually smoother and easier to listen to for many tracks. There is more mid-bass (and perhaps a smidgen more bass) to the sound meaning that everything has more weight, and the highs are smoother compared to the EX. However, compared to the EX and the FXD, it has more of a closed in kind of sound with some particular echoes that sound a bit plasticky. This is really nitpicking because the GR07 sounds pretty darn magical, just in comparison to these other two it sounds a little congested. Nonetheless the GR07 is probably going to be pleasing to the ears for more tracks and its a fantastic all rounder. It's similar in speed and transients to the EX1000.
The FXD80 is by far the most aggressive of the three, with boosted treble and bass. The treble range is overall lifted even compared to the EX1000, but doesn't seem to spike as severely, meaning you get tremendous treble extension and magical energy without as much sibilance. Lower mids aren't tremendously recessed, they just don't really excite in the mix as much as the other frequencies. The soundstage and overall presentation is cleaner than the GR07 and EX1000, with a kind of scalpel blade precision to the transients. However it doesn't create the out of head illusion that the EX1000 does; it just manages to be more cohesive within a smaller soundstage. Actually, the overall presentation reminds me of the sound Bose tries to install in most of its models - bass and treble performance that makes people go "gee willikers". However in this case the price is also pretty jaw dropping.
I really hesitate to say which one is better because it really does seem to come down to preference at this point. I can say that the EX1000 and FXD80 sound like the cleaner IEMs, but the are less forgiving compared to the GR07. In terms of other factors, if it was price / performance, it would be FXD80 > GR07 > EX1000 hands down. If it was ease of use, it would be FXD80 > GR07 > EX1000 again. Build quality would be EX1000 > FXD80 > GR07 (though they are all pretty nice and I'm pretty sure the FXD80 is actually more durable despite feeling less 'premium'). Isolation would be GR07 > FXD80 > EX1000. The EX1000 in particular offers almost no isolation.
As I've said, the GR07 would have been my previous first recommendation to anyone looking for a nice new pair of headphones provided they weren't after a particular sound signature. (If they were after a particular sound signature I'm sure they are picky enough to do their own research). Now my recommendation would be the FXD80 in a snap. The EX1000 is a beautiful instrument, but seems more like a enthusiast's / collectors model than something to live with every day.
As far as my preferences go, interestingly enough the GR07 is actually the kind of signature I prefer. However the FXD80's seat of your pants energy and precision are addictive, and I've found myself using the JVC almost exclusively. (Actually, if I could get the FXD80 build and clarity with the XBA-4 signature and layering I would be in heaven).