I can say this much... I have had something slightly hit me in the ear with the er4s in them. It hurt a little, although nothing serious or lasting. I find it unlikely that you would puncture your eardrum easily, as the shape of the ear is bent and doesn't easily allow the er4 that deep. I'm not saying it is impossible, but it isn't a straight earphone going into a straight ear canal with no resistance... So while possible, I'd say it's unlikely unless you were really slammed in the ear, at just the right angle, in which any iem would probably do damage.
Disclaimer: i am not a medical doctor. So don't listen to me.
I'm with you on one point. Over ear wear. I absolutely love the pfe112. ety could absolutely learn from their design in both housing and fit. It is the most comfortable iem ever in my opinion with the comply tips. And a side note, in the case of the pfe112 the comply tips actually improve the response. Goldenears verifies what i'm hearing in their graphs.
Anyway, if the er4sr housing or cable or both allowed an ergonomic around the ear fit, it would be awesome. Even if it was simply something like the pfe112 ear guides, shaped to work well with the er4, that would be awesome...