I've owned the HF3s for a couple years now and have had the GR07 Mk2s for a few months. Years ago (circa 2005) owned the ER4Ps for a couple years as well and they were my sole portable phone until I tried the Shure S500s.
Maybe after thousands of hours of listening to Etys (generally because they're so well regarded on Head-fi) I would hope I'd 'get it', but I just don't. I prefer everything else I own to them... relative low end stuff at this point, including EPH-100s, FXD80s, S500s. To my ears they come off dull, anemic in the bass, and shrill. And I've tried driving them out of things like my old desktop setup (Metrum Octave -> WA6SE), O2/ODAC combo, and the Dragonfly.
So something about me must be defective to not hear how special these guys are. I still use them regularly - for conference calls with clients because of their mic. Music listening, no way. OTOH, the GR07 Mk2 are my favorite IEMs right now, so it's not as if I'm against a neutral presentation.
The etys are highly tuned for a reference diffuse field frequency response but deviation from the design plug depth would cause a treble peak somewhere above 7kHz, causing a shrill presentation. Rather than try to fiddle with tips to find a tip I can get to the reference plug depth (a lost cause anyway as I would never be able to get them in deep enough) I just EQ the one resonance peak out and they sound much better. Look at PiccoloNamek's "how to equalize headphones" guide for details on how to find that resonance. I wrote an "advanced EQ tutorial" but while it's sonically superior I have to admit it's rather less comprehensible