I've been frantically buying earbuds for the past few weeks in the hope that I can get comfort, high quality sound and a discrete appearance from a pair I'm prepared to spend the money on - the e3c's are at the very top of my budget. Unfortunately there isn't a single pair of earbuds that can really compete with even the cheaper full headphone styles on the market (except when it comes to a discrete appearance). However, these come pretty close and provide good isolation from the outside world.
Much easier for me to keep in my ears than the e2c's. These are very lightweight apart from the cable, which really is a bit too heavy and a little too stiff.
On the whole very good sound but a bit cold and clinical, sonically not so much really superior to the cheaper e2c's as different. If total accuracy is your thing then these are very good. I just find them a little harsh to listen to for any length of time. They handle heavily instrumented music extremely well but small jazz combos sound a little lifeless. Singers like Norah Jones and Diana Krall seemed to lack their normal warmth, while the Buena Vista Social club really comes to life - although a few high sustained trumpet notes are just a little too much. Tom Waits growling vocals are handled superbly, Nanci Griffith sounds congested. Spoken voice is generally superb. Low notes, for example the plucked string of a double base, lack the real hum at the bottom but maintain definition and character very well.
On the whole these are pretty much what I've come to expect from better quality earbuds. In this case I'd say they are (just) worth the premium.