I got my W3 5 days ago and originally felt cable up to Y-split could've been longer, but since cable is much more flexible than the SE530s, it's actually more comfortable being shorter as you don't have (thick) cables (and extensions) swinging sideways constantly.
I suppose you could say I have a big(gish) head and I have to say I find the W3 great, very unobtrusive. Cables on W3 are thinner & softer, of a plastic material that is more malleable, and makes NO noise at all when it moves, like the SE530 do - NO microphonics!!
The cable + extension on the SE530 were far too heavy for my taste, terrible for travelling, and simply quite impractical, IMO. And yes, one thing I like quite a lot about the W3 is precisely that there are no cable extensions, making the W3 incredibly light! - you just don't notice the cables at all.
However, the most important thing for me as for everyone else, I suppose, is the sound.
To me, the overall sound on the W3 beats the SE530 considerably. The only thing I can describe it as is 'more real or natural', the balance of lows/mids/highs is incredible. And I insist, instruments and voices sound very real indeed - this is strainght out of the headphone out of my iPod Classic 160gb.
I enjoyed the SE530 but could not use them for more than hour or so, but perhaps that's just me. With the W3 I can listen to music for longer periods of time.
I've been using the stock large silicon grey tips on both SE530 & W3 which provide the best seal for me, most comfort, and better sound reproduction.
It's great to not have the need to adjust any part of the sound via EQ settings, and just have the EQ off permanently.
In the last 5 days I've listened to lots of different types of music, though mostly acoustic: Classical (Orquestral, Chamber (mostly string quartets) & solo violin sonatas), Rock (from Beatles to Henry Cow), Avant Garde, Jazz (Coltrane, Kenny Wheeler), World, & Pop.
Also, the In-line Volume Control is of a better build quality - the SE530 looked and felt cheap and tacky, and did NOT work properly, as you could not mute sound completely. The W3 looks and feels right, and works perfectly.
On a perhaps irrelevant note I thought that for a £220+ pair of earphones the SE530 looked rather cheap. Yes, the metal box and rest of packaging looked very classy, but actual earphones & In-line Volume Control looked tacky.
By contrast, the W3 packaging is nothing to write home about, but the actual earphones & accessories are of better quality, in my view.
I also prefer the right-angled plug end of the cable on the W3 - something I found impractical on the SE530 somehow, as cable ended in a straight line.
And one more thing, for travelling I find the W3 carry case more practical than the SE530 - the latter being stronger/ more solid, bigger and protects IEMs better, but for me the size and texture of the W3 case is just perfect. Even the zip practically makes no noise when opening/ closing the case.
So far, I'm very, very pleased with my W3, and hope they last a long time.