I find that the FXZ-200 excels with music that has natural bass and not too much compression (or none) in the mix: Classical, Jazz, Blues, some Pop, Blue-Grass, Bossa… well you get my meaning.
From what I hear, when the bass has been processed a lot, has been over compressed, or has been recorded poorly, the experience is just painful. This IEMs act as bass microscopes, which for me is a new experience and one that has me wondering if the sound engineers give a damn regarding how bass is recorded as long as is has the punch that low-end reproduction needs.
when the trunk rattles enough... the bass is good. i've been to several concerts where the 'bass' was just a bunch of one-note mush. imho lots of 'sound engineers' and 'mixers' haven't been told that basses play NOTES!
rant over - long-winded way of saying "I agree" with you. There's a huge gulf between an iem that allows you to hear what your rig plus recordings actually sounds like, vs whether it makes it sound the way you want it too. Usually the difference between folks who listen to 'artificial' vs acoustic music- and there's nothing wrong with this. it just seems to me to be the way things are.