Update. So I got the hf3's today. Firstly on the headphones themselves. They seem well built, I still like the large triple flange eartips that I've gotten very used to on the ER-4P best and will be sticking with these. I find the ER-4P's easier to insert due to the longer stem. The hf3's basically go all the way in with my ears when fully inserted.
As everyone has already mentioned, yes the microphonics are clearly better controlled with these compared to the ER4's. The wires are more rubbery and so seem to absorb and transmit less than the ER4's. It's still there, and I will still likely use the shirt clip (can't use the ER4's without them) but it is a welcome improvement. The mic and controls are as advertised. Not sure on mic quality but frankly I don't care so long as people can hear me decently which I was told during my one phone call with them that I sounded just fine. Good enough.
Now for the sound/audio quality and excuse my basic way of describing it as I don't even know the correct terminology but I know what I hear. Clearly these are brand new and not worn in like my ER-4P's with hundreds (or maybe thousands?) of hours but on first listen the sound profile to my highly untrained, non audiophile ears sound familiar but at the same time quite different.
Upon initial listen the thing that jumped out the most to me was that the bass was definitely fuller, had more oomph so to stay. Not a vast amount but clearly noticeable. It also seemed to better flow into the mid's, they seemed more harmonic together. The treble was also good, I wouldn't say spectacular though. The ER-4P's highs are quite a lot more pronounced in my opinion. Overall, I think the ER-4P's have a broader sound spectrum, like they have a more extended range compared to the hf3's. I find this both good but also not so great depending on the song, type of music and audio quality of the file to begin with.
Another thing I noticed is that the hf3's seem maybe a tad louder at the same setting as the ER-4P's (i.e. at 50% volume), this must be due to the lower 16 ohm impedance vs the 27 on the ER-4P's.
I listened to various kinds of music and bitrates (though mostly at higher 256 or 320kps mp3's) to determine the sound. Some tracks included Terranova - Bombing Bastards a trip-hop track with vocals by Tricky, Adele - Set fire to the rain, Radiohead - Street Spirit, Rise Against - Satellites, Rage Against the Machine - Wake Up, Nas and Damien Marley - Patience, Nas and Damien Marley - Friends, 65daysofstatic - 65 doesn't understand you (prog rock/electornic), Tomaso Albinoni - adagio in g minor (classical), Nick Warren - Balance 18 CD1 first 10-15 (house music) etc. So quite a varied mix.
WIth the classical music the ER-4P's are hands down better. They carry much more of the emotion of the strings and violin for example due to the greater emphasis on the highs. On Set fire to the rain the ER-4P's are generally more revealing with the various drums, cymbals, and beat sounds. However ghe hf3 are close and still have the same detail you just have to pay more attention and its quieter, the ER-4P just throws the highs/details straight at you basically. Sometimes I find this a little fatiguing like if I'm doing other things and not just listening to music. I liked Radiohead - Street Spirit on both, depending on my mood (bass vs. brighter vocals) I may prefer one over the other. Rock songs I typically preferred the hf3, I think the ER-4P's can be a little bright. Rap was mixed and the hf3's work well but the ER4's do vocals/voice better so really it's a bit of a trade-off. Vocals/voice sounds more life like on the ER4’s, it seems to have more detail and hence carry the emotion in the human voice better. This seems to be a recurring theme, the ER-4's are just more revealing. Its subtle but its there. The House/Electronic music I would have thought that I would like the hf3's more but I think the ER-4P's may be ahead again because of the greater clarity in the highs and higher mids that create a broader soundscape. However, I can see the hf3's clearly being favoured on some days/moods if I want more bass and slightly more subtle detail and highs .
Overall, very tough call but the hf3's are clearly a keeper and well worth the price. I would agree that these are like 90% of the ER-4P's with the 10% being the difference in detail and highs. The ER-4P's sound different enough that they may be worth keeping as-well, especially for classical music and for vocals, they are simply outstanding. Overall the ER-4P's do have an edge and worth the price difference for audiophiles I would conclude. I can only imagine what an amp and the P to S converter will do to them. I will give it some thought and A/B both to determine if I should still keep the ER4'S, I am undecided. I may get the 4S converter and an amp if I do decide to keep them
Sorry for the long post. I have no interest in charts, diagrams and numbers/specs so I'm not sure what those may tell me or anyone else. I simply judged the sound with my ears and I will clearly need more listening time with both sets to get a better understanding of the differences/similarities. Hopefully this will be helpful to some out there.
Edited with more comments.Edited by starlan - 12/10/12 at 9:31pm