I've been wondering about these issues myself, at least in part because I'd like to try both of the westones, but have not heard either. i do have ie8s and shure 530s (along with some other stuff), and would be curious how the westies compare.
now for what I think explains some of these sonic disparities. the sound of an iem (or any audio component) is going to be a function of both its amplitude response (aka frequency response) and its phase response - time domain stuff.
an iem with better phase response can sound like it has more bass than one with accentuated bass response in the frequency domain, because the overtones line up corrrectly, and the brain will "fill in" the fundamental.
hard hitting bass, and good impact on things like bass drum whacks isn't from the bass range, it's a midrange thing because the overtones are in phase and give it the leading edge...
so, i think that a lot of the disagreements about the sonics of some of these iems, apart from fit issues, are phase-related, and alter the way people perceive and describe the sound of various iems - e.g., the 530's being seriously rolled off in the treble- i think it's largely that the treble is in phase, and doesn't stick out as much as in other designs.
imagine a barbershop quartet (not my thing, but a good analogy).. where the four singers are singing at the same volume, but are off a little bit from being in exact unison - that's what i am trying to get at with the phase thing - it effects how we perceive tonal balance as well as timbre, and also effects how we hear soundtage and imaging.
just my two cents worth....
