I actually do DJ, and I find that the V700s are not appropriate for me. They are bulky, weak and uncomfortable. They flip around for side monitoring, but they don't do it very well, its a bit awkward. They emphasize mid-bass, so assuming you have a stereotypical thump thump thump house bass-beat, then it sounds like it has a lot of bass, but electronic music (at least, the electronic music i find to be stimulating) has a lot more going on in the bass region than thump thump thump, and all that gets muddied up.
The then the V700s have going for them is cool looks. DJs looks damn slick wearing them. Which is, of course, why most of them BUY the V700s. Many DJs aren't really that interested in sound, which is why they buy Gemini turntables, and numark mixers.
Like people have said, if the V700 was 50$, it would be a good buy, and useful for some starting off DJs. But at 60$, the Sony V6 (or my 7506) is a much better choice for DJing, more accurate, pretty good isolation, more durable and more comfortable. It has side monitoring abilities, it folds up and has a coiled cable. Its not as cool looking, I'll admit. The Senn HD280s are nice too. I've never used them for DJing, but I gave them a good listening at the WoH tour. They sound good, and they are built like a tank. Better isolation than the sonys too.
Open headphones are right out for DJing, not possible with all the noise around. And Etys, despite their good isolation, would NOT work for DJing, you need to be able to put them on and take them off very quickly, with one hand, which isn't the case with canal phones that need to be carefully inserted each time.
Anyway, the V700s would be cool if they were a lot cheaper. Sony made a very neat looking headphone, and marketed it very well toward the DJ market. It was not priced by what its true value is, but rather, the price was chosen so that it would be expensive enough that you could say "Yeah man, these are like, the awesomest dj phones, they cost me like, 120$, but I gotta have the best man." and have people nod their head and say "Wow, 120$? He's really dedicated to his djing" and yet they had to be cheap enough so that lots of people could buy them to keep them popular. They chose a good price-point for that end. Too much cheaper, and too many people would have them, removing their 'elite' feel, but too much more expensive, and not enough people could afford them.
Anyway, even DJs require a real headphone. I'm totally down with the 'right headphone for the right job' idea, but I'm afraid that the V700 is not the right headphone for any jobs I can think of.
peace,
phidauex