I've had the cable untwisting issue occur with my W3, also. However, though I purchased mine 2nd hand from another Head-fier in early March, and though I don't know/can't recall when they were originally purchased, I'd have to imagine my inherited set are from early batches of the W3, also (likely November-December 08). So if the suspected trend above is accurate, I doubt my specimen bucks it!
The unravelling/untwisting I've experienced tends to happen at the ends of the cable, where it finishes at the monitors and/or cable jack (I've had it untwist at both sites several times). This would logically and physically make sense as it's where the cables end/start and so where their twisting starts. It's also where more of the weight is- earpieces and cable jack, respectively- that could aid/catalyse any motion and/or force needed to cause/start the unravelling, and, of course, the regions of the cable that are naturally going to be twisted and rearranged and shifted about etc, as you use the headphones/in everyday use and appliance of the IEMs and cable (when untangling the headphones and/or geometrically setting them up to be inserted in your ears, for e.g.). Still, though explanable, it's a little unsettling, at first, to think that a product that has cost you so much and is reputed for being high-end and top calibre can start to come apart like that, and, after only normal useage of the item and no abuse and/or purposeful appliance of force or motion that could cause the unravelling to occur. I've also had the W3 cable untwist a few times (in a few different places) further along/into it's length and away from it's respective ends. However, all these untwistments- be it at the cable ends or otherwise- have always been minor and localised (nothing drastic or anywhere near comprehensive or comprehensive threatening) and so easy to retwist back in place.
So that's all I do now/is what I've resigned myself to, just being relaxed about it (via the experience and understanding that the untwisting doesn't damage sound quality or an other aspect of the phone's condition or performance) and when an untwisting occurs/starts- which is relatively infrequently-, twist it back. As it is, this is no biggie. If the cable didn't twist back/stick back in place (for a decent length of time) and remained untwisted, then I'd definately have a problem with it! However, as this isn't the case and shipment back to the US for repair/replcement not being desirable, I'm happy to put up with this little bit of infrequent maintenance. Of course, if the untwisting does occur permanently, I will have no qualms in claiming a repair/replacement under warranty.
N.B.// The cable is certainly durable physically and functionally, if not in maintaining it's design/physical state implementation, being, as already cited, light, flexible and totally unmicrophonic. Also, my W3 cable got trapped under the leg of a chair I was sitting on when I was using them with an extension cable at my family desktop, probably, as it went unnoticed, for about an hour, and survived! So I can vouch for it's durability in that regard!
