More the venting I'd imagine for openness. Coherence, yeah no Xover and no funny weird aberations in the FR.
Really, think about what you need for out and about situational awareness. Low isolation and cheap/disposable when lost or crushed out in the wild.
For seal I found three levels of fit. 1) No bass/thin slight harshness, mostly due to the ridiculous housing keeping one from adjusting insertion depth. 2) Better seal, more bass, less treble bite, mids sound hollow and thin. This is fake seal, when the tip feels right but there might be a fold usually if the silicone tip is thin or wrong diameter still messing w/ depth. 3) Best seal/tip, bore not too wide, bass and treble good, mids full and present, coherent sig from top to bottom. This one gives it close to a HD558 sig for $7 in an IEM almost matching my favorite neutral budget IEM, the Sunrise Xcape v.1 ($65; discontinued) but with less refinement. I even enjoyed the Sunrise v.1 more the the 558 but it wasn't as open as either the 8320 or 558. I think it's worth the work to find the right match and not dismiss it due to being $7. Assuming it's not messed up w/ channel imbalance and whatever else.
Of course, I go amped w/ high gain so I have no idea how boring it might sound from a Clip or iPhone by comparison.