I know this is a long-dead thread, but these new-to-me E2's have found a permanent home. Due to limited time, I've only been able to compare them to 1 other set so far, the HE6se V1 (plus my other headphones are closed-back and not planar). Honestly, it's been a blast a/b'ing them and I didn't think 2 planars with such similar styling could sound so different. For the purposes of this comparison, I'm using the suede pads on the E2 and fenestrated sheepskin on the HE6se.
Where the HE6se is bright and sparkly with 3rd-row seats, the E2 is dark and full-bodied with 1st-row seats. While the HE6se is well extended in bass, its impact is dreadfully light compared to the E2, which also has that immaculate planar bass extension. IMO, the suede pads on the E2 bring it pretty close to audiophile bass-head territory, which I love. As we move into the mids, it's amazing how different they are. Vocals on the HE6se and crisp, airy, and represented in my head as a well-defined point in the headstage. On the Ether 2, vocals are much "heavier" and full-bodied and are represented in my head as being much wider - less a point in the headstage and more like a 10-degree slice. Vocal details on the HE6se shift toward the treble, whereas vocal details on the E2 shift toward the bass (if that makes sense). As we get into the treble, the HE6se initially comes off as much more detailed and airy. You can hear the space around the notes and they are plucked like planars be - dangerously close to shrill at times, but almost always controlled and non-sibilant. On the E2, treble is not emphasized - it's a dark headphone regardless of the pad choice. But it's not that the treble doesn't have details - it does, loads of details. It's more that the treble isn't sparkly and you don't hear the space around the notes with the E2. The treble is there, it's beautiful, but it's not emphasized. Overall, the E2 has been my preference on the SET Mogwai Rev2 by far. On SS Jot2 they both sound great but have completely opposite strengths. For my preference, I like the E2 more, but would go to the HE6se if I was craving airy, treble-centric music. HE6se has the wider headstage, but to my ear the E2 is on par in terms of imaging and I love the thicker, more romantic presentation. E2 wins in terms of stage depth and height. E2 is way lighter and more comfortable.
On the matter of pads, suede are the extension pads - the emphasis is on sub-bass, treble has more energy, and overall probably a bit U-shaped but no big peaks that I can hear. The fenestrated pads have a huge emphasis on the mid-bass and the vocals, but the spikes are an issue for me. cymbals and other instruments in that range can sound anemic and the treble extension is bad. I honestly haven't tried the stock pads yet.