Just to feedback a bit, a little while after my first impressions on the W4.
These earphones just seem to get better and better. The subtlety in their presentation of music is a joy to listen to.
As I listen to a lot of metal (which can be recorded poorly), I found that the W4 are less forgiving of low bitrates and bad production when compared to the W3. However, they still are forgiving, which is perfect IMO. They allow you to easily differentiate good production from excellent production, and poor production is clearly evident when listening...BUT somehow their presentation somehow manages to make almost all recordings pleasing to listen to (this may be due to the slightly smoother/warmer tone when compared to more analytical IEMs, which some may not prefer.). This works for me though, as my musical taste is really broad and spans lots of different qualities of recording.
Perhaps this comment may not make sense, but the soundstaging and instrument separation seems to be better preserved in outdoor use with the W4 when compared to the W3. It's inevitable that sound leaks in, regardless how good your tip fit is, but the W4 seem to preserve soundstage, whilst the W3 seem to get muddy and 'flattened' with the presence of background noise. Weird.
Also, those who crave more bass impact should definitely try the triple flanges. My assumptions were slightly off in terms to their impact on the W4 sound. I had predicted they would compress the sound like they did on my W3, but they managed to remain balanced and clear, without the bass rolling over other details. In fact, the added isolation brought out more shimmer in the highs and some added details in the mids without 'scooping' the sound too much. I may shorten the stalk even further though, as the longer the stalk the further away the soundstage seems to be. I prefer the soundstage to be a bit closer and intimate, so some further trimming is in order. I have some triple flanges modded to biflanges as well, but don't recommend these as they seem to just muddy the sound and loosen the bass. I think the third flange really helps maintain a tighter sound - but YMMV depending on comfort and fit.
And as an aside, I've been using these through my Macbook Pro (no DAC, just the volume attenuator to kill the hiss) and they really work well with Amarra. Highly overpriced piece of software for what it is, but it does significantly improve the sound IMO, with the W4 at least.
Regarding the comparisons above with the Shure's, I auditioned them briefly side-by-side with the W4. I felt that their bass was good but with not as much resolution as the W4 - perhaps with more bass impact though (bear in mind the W4 did not have the triple flanges on them during the test). The mids obviously shone through, a bit too much IMO. Perhaps with some of the poorer recordings in my library they sounded scratchy. I guess the mids as a specific frequency band aren't forgiving on the Shure's, I can imagine them being fantastic if all you listen to is well-recorded classical or female vocals. The trebles were also there but lackluster, I think this was because of the instrument separation/soundstaging, which I perceived as more conical in front of my face than the wider 'wrapped around my head tightly' W4 soundstage. I think things like the hihats didn't jump out at me as much on the Shure's and the bass lacked the smooth control of the W4, though the bass was quite enjoyable for casual listening, on critical listening the bass didn't seem to perform as well - particularly apparent on bass heavy music like Venetian Snares - Detrimentalist or some good old Benga.
