They only go so far before hitting an end point in my canal. The er4s would go farther, but I'm not forcing these, just pushing them until they don't go any farther. When I do this it verifies everything I though about pressure.
I've been wearing them shallow, and the sound is immaculate. When I wore them any deeper they would sound bassier, not much, but overall a touch warmer and less detailed. However, if I push them in until they don't stop, which is farther than most earphones would probably be worn, they sort of fall into the inner part of my ear more, which as they do, they release pressure and equalize completely. When this happens they sound every so slightly smoother and bassier (i'm talking slight) but overall essentially the same exact sound. The ever so slight tilt is probably expected from the depth and closeness to the eardrum, but the fact that they are less bassy all the way in compared to half way in shows that the pressure for me is more of a determining factor.
This is cool, because as you see they are very easy to wear over ear this way, which reduces all cable noise for me completely and is more secure in my ear. If I had to give an accuracy score (just making this up off my head) the shallow fit being 100% would give me about 98.5% deep and maybe 96% middle of the ear. So in any position they're amazing, but I prefer that extra level response and tightness from the deep or shallow fit. I can "almost" get this exact sound in the middle of the ear with other tips like the mh1, because they seem to flex more and allow easier pressurization. But the middle of the canal still is the tightest spot for me and generally give me more pressure buildup.
Anyhow, in all of this experimentation, I actually prefer the mh1 tips now. As I said, they flex a bit more and to me that gives me a bit more comfort. They're also longer, so easier to get to the deep fit. But I found they sound identical. Any differences I heard before were probably from the way they fit. The same way they sound bassier in the middle of my ear from pressure is probably how they sounded because they are longer or something. Comparing them now, I can't tell any noticeable difference between them with the same fit on each. If they are bassier or something, it is minuscule in difference and the comfort is better for me, so I prefer them. But again, they sound basically the same to me as far as I can tell now.