Just received mine. Half an hour with it. The sound signature of these IEMs are truly interesting indeed.
Have to agree 100% with HeadphoneAddict's review. It's just spot on for a very nice joyride. The bass is just what I want on IEMs. The mids are not REALLY forward compared to the ER4S. Instrument separation is wonderfully done well. The amount of detail given by these headphones are sufficient to my taste. It's the only other IEM which can pick up certain details which only my ER4S can pick up. The instrument placement is interesting though.
On my ER4S the positioning is perfect like a live band performing.
Whereas the Westone 3's, the bassist's amp is located more forward. Ocassionally the the bassist's amp would be in a line with a vocalist's. But I blame the recording for that.
One thing I dislike about the Westone 3's. If the ER4S is like a sharp edge, the Westone 3's is like that same edge, sanded off to make it rounded. It's a good thing for badly recorded music as well as guitar solos. But it's a double edged sword. It makes acoustic guitars which are recorded well, sound like the guitarist changed their acoustic guitar to some cheap budget acoustic guitar. There's that certain resonance and crisp that acoustic guitars have and the Westone 3's just degrade those wonderful elements.
For everything else however, two words, natural and musical.
I'd use the Westone 3's for everything except acoustic music or anything with an acoustic guitar as the main instrument.
Perfect IEMs?
No.
Best universal universal IEMs?
Yes.
Note I said universal universal.
Which I mean by Best all-rounder universal IEMs.
The SE530s may be good for classical music but not for some music.
The UE Triple.fi 10s may be good for rock or some upbeat music but not for some music.
But the Westone 3's however, manages to pull it off for all genres. Good for every genre. Best? I don't know. I don't have other IEMs aside from my ER4S.
All I know is, the Westone 3's are truly worthy of being called universal IEMs.
But I'll keep my ER4S for acoustic music.

Cheers.
Time to TRY and enjoy Annie Lennox's "Into The West"
P.S. Using the standard comply tips. The longer one. I have deep ear canals.