I've no experience with the W3. I would suggest looking at the 170 IEMs reviewed and compare the W3 to the SM3 (even though it's v1, it's the same sound).
The new housing is way better in quality. It feels a little heavier, the plastic isn't as flimsy and looks more solidly built. I wish it was clear, but I definitely remember the v1 felt a little fragile (and turns out it really was). The plastic is a smooth finish.
My mistake I meant the W4.