I only auditioned the W3 for about a half hour with comply tips, but was A/Bing with my IE8 using the same source (Fuze -> custom LOD -> Provided RSA amp) and here are my observations:
- IE8 has a much wider soundstage and a more laid back presentation
- W3 has better instrument separation and, as the mids are more forward, the details are more readily apparent
- The IE8 seemed more dynamic
- The IE8 was smoother in the mids and treble
- The W3 was ever so slightly more transparent
I preferred the IE8 as all the above differences were minor except the presentation and soundstage. Of course, presentation is a personal preference, but the soundstage was much wider with the IE8.
When I did this comparison I was using comply under silicon tips, but now with the tip extenders the IE8 has improved significantly in instrument separation, transparency, and soundstage width. The mids are also a little more forward, so IMO the IE8 would beat the W3 at everything! I know there will be some that don't agree