Okay, some random thoughts on the ER-4P. While I am not thrilled about how far they stick out of your ears, the overall build quality of these is much nicer than I was expecting and I'm okay with the fit. I think I like the cord just as much as the Shures. I don't run or jump around so microphonics are not an issue for me.
Perhaps it is my ear type but I find very little difference in sound with different Ety tip types versus different Shure tips. The clarity and detail on these ER-4P's is astonishing but I could see how it wouldn't be for everyone. In fact, if you took 50 random people off the street and fitted them with E4 and ER-4P, I think majority would go with the Shures. But that is not saying the Shures are better. I do not find ER-4P to be fatiguing or harsh at all. I actually made this switch (from E4's) after hearing the more detailed ER-6i's and felt I had to take the full plunge to ER-4P. It's like hearing Ety's almost ruined the E4 experience for me in some respect. There was nothing I didn't like about E4 until I heard Ety. All of the sudden E4 wasn't enough detail anymore. Go figure. It's hard to explain. It's like the E4 experience is like listening to a concert at a "dark" smallish (great acoustics) auditorium, 10th row center while the ER-4P is like sitting on a chair in the middle of the band in the recording studio. I'm not sure I could say one is better than the other. There is a lot to like about both and very little to dislike about both as well (IMHO). I think the "weaknesses" of each are easy to overcome. I will say that I think the ER-4P sounds better unamped straight out of a Nano (rock setting). The E4's are almost too warm out of the Nano and veils the highs a little too much for me.
With comparisons to ER-6i, as many have stated, the main difference I notice is slightly harsher highs on ER-6i (but certainly not bad) and weaker build quality. I will keep the ER-6i's as a back-up pair or use in harsher, hotter, sweatier environments. Tough to beat for $90.