Pros: Great sound, pretty neutral, extended, clear, great all round, deep insertion, replacable cables
Cons: Neutral, deep insertion, may be sibilant if not properly inserted (deep), grainy compared to high end sets, replacable cables
Summary: These require deep insertion. Once inserted they are neutral, extended and adaptable. They don't really have any sound signature that shines through recordings but instead adapts to what is being played. Great for the price. Very versatile.
I bought these used from a fellow head-fier. Coming straight from the GR07, they sounded bright, dry, flat, grainy and unrefined. However, just 2-3 songs into the audition I forgot all about them. The brain is great at getting used to small flaws. After that I just heard the great sound. They really show you what's in the music. If the music has plenty of mid bass, they play it for you, if the recording is cold and sibilant, so are they. A great iem at doing what they are told to do. At first there was one thing really bothering me, sibilance. After really pushing them in, it disappeared. I previously tried with some paper pushed between the nozzle and the tip to absorb the treble. That muddied up the mids a bit, killed the extension and increased the bass (something I think many would like actually) but for me, they lost their real pros.
I'm using them with the orange hybrid clones, a very deep insertion (for me not used to it) is required to get rid of the sibilance. The cables are a pain in the ass really but with some duct tape or similar it's fixable. Otherwise they just fall out if you're moving too much without being careful about the cord. The form factor is pretty good with small housings that feel durable. Wearing over-ear is my preference even if the ends point in an odd direction. Wearing them down produces too much noise for my taste but if I'm not moving it's fine.
NOTE: I'm just writing this a bit casually. The sound impressions are mostly from memory but I just had to listen to them to confirm. Really enjoying them.
Bass: Extended, quite flat without the bass boost or mid bass hump. Texture is quite good but lacks the "organic" (in lack of a better word, that's how I always think of it) texture and decay of the GR07. Quite fast response and good impact. No bloat unless it's in the recording. What really surprised me was the ability to produce a warmer sound with more mid bass in some live recordings where I've previously thought "hey, there's some powerful impact in the bass here".
Mids: One word "neutral". I've always had a hard time describing mids. There is a good balance between the lower mids and the higher mids. They neither sound warm, nor do they sound cold. Though they can be anything if that's what they're told. (OMG did I just rhyme?) The resolution isn't the greatest compared to higher end sets like R-50, UE900, GR07 or Re0 but like I wrote before. You get used to it and soon it's not really any problem, I don't feel that there's anything lacking there. Detailing is good. Overall mids are great.
Treble: Here's where the real issue lies. If they're properly inserted there are only hints of sibilance, mainly in the "sssssssss"-department and some cymbals. Otherwise they're fine. Not emphasized, the treble just blends in with the rest of the sound. However, if they're not inserted properly. There is some eardrum cutting sibilance with every "s". Compared to better extended sets like 2/3 blocked UE900 out of a C&C BH output 2, R-50 or Re0 they sound less airy less sparkly. However the R-50 (stock tips, don't have comply yet) and Re0 (hybrids) are more offensive in other ways in the high mids/treble.
Insane price/performance. Really. Buy them.