While I'm still not entirely settled yet, I've spent enough time to note some definite changes between the RS1i and e:
*Sound signature is very different. I've owned the 80, 225, 225e, and RS1i, and they all had a fairly similar balance. The RS1e is the most dramatic departure from the usual Grado sound of all those models; the treble is very muted in the upper range, to the point where it almost sounds "dead" with no extension past a certain frequency at all. This means that transient details, like the little sounds of guitar picks/string squeaks/etc., are very muffled.
There's still that classic upper-midrange hump to keep the headphones sounding bright, but the lack of high treble extension sometimes gives the phones an oddly congested sound and is part of the reason I thought strings sounded so awkward when I first started listening. This is the single biggest fault of the RS1e, and I'm having a hard time looking past it.
The bass and especially the lower-mids are much more pronounced, which gives the music more body and weight. These ranges generally sound more powerful and full than the RS1i, but sometimes the lower mids seem to overwhelm the mix; this probably wouldn't be an issue if the upper treble weren't so rolled off. I suppose the up-side of this is the the e is much more neutral than the i.
Combining the extra mids/bass with the less airy treble, the sound is much more solid and stable than the RS1i and more "up close" and in your face than before. In comparison, the recessed mids and more crystalline treble of the RS1i make it sound more ethereal, cold and distant.
*Soundstaging is better. A lot of people have said the e has a wider stage, and while that's true, it would be more accurate to say that the instrument placement is better. The soundstage sounds very well organized in that the instruments seem to have more space to themselves and the extreme left to right panning is wider than on the i model, but the lack of treble extension can make the soundstage actually sound more closed and narrow for tracks with a lot of high end information (like large, sparkly reverbs).
To use the cliche soundstaging analogy, you could say that the RS1i is like sitting a few rows back in a smaller theater- there's more distance, but the sound doesn't have as much room to expand outward. Compare that to the RS1e, which is like sitting a few rows closer but in a larger theater with grander acoustics.
*The e's are easier to drive. I get an obviously louder volume from the RS1e than from the i while at the same setting. I would have assumed the larger driver would make the opposite true.
*The overall sound is noticeably smoother and with better midrange texture/detail. Complex synth sounds in particular definitely have more nuance to them on the RS1e and there's a pleasing clarity and purity to the sound. It's hard to describe, but I assume this is what Grado meant when he said it was as if a veil had been lifted on the e models.
It's really hard to decisively say which is better. The e model definitely has better soundstaging, better detail, and a fuller, cleaner sound. Unfortunately, the awkward treble extension is very hard to adjust to and I keep wishing I had an EQ in my system to boost the highs... Who would ever suspect they'd need to do this with a pair of Grados?
On the plus side, the crushed earpads actually returned to their proper shape after a few days out of the box and the bowls have reformed, and again, they are great looking headphones. I'll have to decide in the next day or two which model to keep.
For reference, I listened on an analog system that includes an MMF-5 table, a Bottlehead Eros phono amp, and a MAD Ear+ HD, which I consider to be an ideal setup for an RS1. Or at least as ideal as I can afford...