Not sure if the sound would be your cup of tea but yeah it is interesting. From jokers review thread the W4 seems to take a little of the best from the Westone product line such as the W3 and the UM3x. I guess i was rather harsh on the treble but it would have been nice to have a little more sparkle in the highs. Oh well, it's nice to have a mid centric IEM that works as an all arounder in my stable.
Headphone Reviews and Discussion - Head-Fi.org
I've been curious about Westone having never tried them before. I'd probably go for the UM3x, though you make the W4 sound interesting too.