An improvement: Switched the stock double flanges for the medium foam monster tips. Sibilance is definitely reduced, and treble sounds more linear without as much emphasis on cymbals crashes, while retaining enough presence for accuracy.
A criticism: Tonality in the mids is still a bit warm. It's very slight and probably wouldn't bother most people, but to me etymotic mids are most akin to actual voices, perfectly flat and natural. With a ~2-3dB eq bump at 3kHz, the ASG-2's mids are much closer to accurate imo.
About mids: I have a relatively flat pair of speakers, and I've had the good fortune to spend time with quality full-size headphones, including the SR-009, SR-007, LCD2, LCD3, HD800, HD650, etc. While these phones definitely have their differences, they share a common emphasis on mids compared to most iems I've owned. In fact, it was experiencing these totl head phones that brought me to the realization that many iems bring an artificial boost to the treble and bass, while leaving the mids slightly behind. Listening to my speakers supported this realization as well, that sound hitting the ear in a diffuse field tends to emphasize the mids.
So which iems have mids like the totl headphones? In my experience the ER4S is the closest, although bass response and extension could be improved slightly. When I compare the ASG-2 to my speakers, the mids of the ASG-2 sound pretty obviously less emphasized at ~3kHz.
Jeff Mangum from Neutral Milk Hotel has a good voice for testing mids (for me especially as I've seen him live). The album In the Aeroplane Over the Sea is very mid-centric, and to my ears his vocals are lacking just a bit higher up on the ASG-2.
A test: Try eq-ing 3kHz up about 3dB and tell us what you think about the sound. I think it's quite an improvement that evens out vocals, resulting a more accurate realistic sound. I'll try to tweak it a bit more, but generally I think less is more when eq is involved.
Again this criticism is about a minor aspect of the sound, although at this price and performance level the minor aspects of sound can make or break the entire auditory experience imo.