It’s hard to say what the actual effect of the bone-conduction drivers is, since there’s no way to turn them off to compare.
What it is supposed to do is “embellish” the mids and treble. And it’s not really clear what is meant by “embellish” (other than an assumption on my part that it is an improvement).
Though I can say that the mids are incredibly well textured and engaging and the mids and treble both are richer and denser than any other IEM I can name off the top of my head, without any hint of slowness, congestion, nor loss of detail or agility.
I don’t consciously feel anything on a physical level, and while the bass has plenty of rumble and growl (more so than the tia Fourté for example) I don’t think that’s coming from the bone-conduction driver.