Just opened my W3s for Xmas (well, last night) and after a couple of hours of listening, two observations:
One, I can see why some folks don't dig them, because the tips are so critical in getting the best sound. I tried several foamies and other sleeves, but until I modded the tri-flanges to bi-flanges and trimmed the stalk a wee bit, I could not get the max SQ from them. My ear canals are different sizes, and my right ear is much more problematic. So finding the right sleeves was tricky. I also have an old pair of soft silicone custom sleeves from my FutureSonics' EM3s (going way back), and at first, the silicone sleeves sounded okay. But in the end, too thin with the W3s, and too ugly (they make the W3s stick out way too far).
I do have some old Comply P-Series "shorts" (same size as T400s, but with the smaller sound tube) and they worked very well. But I don't see them listed any longer on the Comply site. I only see standard and thin in the P series. Also tried the T100 smalls, and they are a wee bit too small.
So for now, the modded flanges are the best sleeves for me.
On the SQ front, to me, these phones really reveal poorly recorded tracks, much more than my other IEMs I have owned. So I do agree that some tracks sound somewhat muddled with the W3s, but when they are matched with high bitrate, quality engineered tracks, wow. So they may cause me to rerip even more of my tracks from CD to Flac, Apple Lossless (on my iPods) or at the very least 256/320k vbr. But even high quality rips sound lousy if the recordings are poor, and the W3s have the ability to have that happen.
So, in my view, these are much less forgiving IEMs, but when they are at their best, especially with certain musical genres (swing, jazz, acoustic, etc.), they sound fantastic to me, best IEMs I have heard (never owned the TF10s or SE530s). I don't notice the bass bump others mention, but maybe it just doesn't bother me. I love the bass on the W3s, in fact.
I just need to listen some more, and enjoy.