Can't wait for your impressions on the EM4s @average_joe.
Btw, do you hear a clear advantage of having multiple-ba drivers on a single frequency response like bass, than having one ba bass driver or shared by other frequency response (mids or highs) on a single-ba driver? How about the number of cross-over configurations?
I can only compare 2-1ba, 3-3ba and 8-3ba (driver to cross-over configuration). And what I can hear is that transparency and layering is handled very well by iems with more ba drivers. I hear on my iems that the more drivers they have, the greater they handle complex music easily - separation of instruments is clear but coherency is less. Like for example the bass on my JH16, it is rendered with a whole note sound, that's why it sounded very bassy to some coming from a balance iem, maybe the bass frequency is sliced up to each pieces of the bass drivers, also the same with the other spectrum like the highs and the mids. I can't say it's advantage is on details since my dynamic iems can do that very well, like the EX1000.
I'm just assuming and maybe I'm wrong but with your experience is this also your finding on your other ciems if they are done very-well (excellent fit, no driver problems)?