I was put off by the rotating nozzle at first but I've come to prefer it as now I can take off the earpiece temporarily by simply rotating it. On some demos it does seem to get more loose over time though.
At this point I can't do a direct comparison because my IM70's cable is broken. I just called Audio-Technica Taiwan today and purchased a replacement HDC1 as few if any stores sell it.
My first impressions were that they were quite warm and boomy in the bass, after trying the ATH-LS70 and LS50. The midrange seemed somewhat recessed at the top but less so than the latter two IEMs, with more air in the treble. From what I recall the LS70 has a tad bit more sub-bass than the E40 while the LS50 is more midbass-focused and a tad more boomy, but both LS IEMs seemed a tad too veiled for me (I don't recall the IM70 being that veiled). Of course, there's always the good old filter mod which some people say clears up the veil. The E40's soundstage is a tad narrower than the LS dynamics, but has a lot of depth. Despite the intimacy it is quite good at positioning and instrument separation.
The seal isn't easy to get perfect but I think it is much better than that of the IM70. If I flex my forehead or ears the seal doesn't change much and with the stock tips I feel they stay in my ears very well. If you're in a very noisy environment they still don't isolate the sounds of sirens and cars going by unless you have music playing loudly
I also bought the 1More Triple Driver recently. In terms of detail and resolution, I think it is a step above the E40, which sounds veiled and coloured in comparison. However, the 1More is REALLY unforgiving of poor recordings, especially bass distortion or crackling, hardly noticeable on other IEMs. The crackling is noticeable on Coldplay's Hypnotised, for example. The upper mids are also rather hot on the 1More, not fatiguing but my ears seem imbalanced in this region that I hear sibilance more on my right ear. That said I think it is the more neutral of the two IEMs as its bass is not as boomy and treble more tame despite extending higher up. I prefer the E40's form factor, removable cables and durability (the 1More's metal design is nice but more prone to scratches) - the E40 also has better sub-bass extension.
EDIT: Philips SHE3590 eartips seem to tame down the midbass while adding some more sparkle to the highs.