I've had my HE-1000 for over a week now and have enough of a feel for them to put down some thoughts. I also have the HE-560, had the HE-500 for a few years, and borrowed a stock HE-6 this week.

I feel the HE-1000 are HE-560s on steroids. Very similar type of sound but just does everything better. Switching from the HE-1000 to the HE-560, the sound is immediately compressed, less soundstage and less separation between layers. I also felt the HE-560 are a pretty good value given how much less they cost, but overall the HE-1000 is quite noticeably better in every way.

Compared to the HE-6 though, it's very different. In similar ways that I thought HE-500 and HE-560 were different. Both the HE-500 and HE-6 have more impact and attack than either of the newer 560 & 1000 as many mentioned. I do find that other than attack/impact the HE-1000 does everything else better than the HE-6. After careful volume matching, switching from the HE-1000 to the HE-6, the soundstage is smaller, the sound is less transparent and layers are more compressed. The sub bass is also sorely missing.  If I bump the HE-1000 volume up over the HE-6 by 1-2db, it covers up the slight impact difference between the two headphones and while still a different presentation, I prefer the HE-1000 overall to the HE-6. I also did find the more aggressive treble on the HE-6 to be a bit fatiguing after a while, despite finding it to make the sound alive and dynamic. I thought detail and resolution were similar for both. Again this is with a stock HE-6.

Overall, add the comfort advantages and I feel the HE-100 is an overall upgrade to the HE-6 although at a great cost difference.

I also compared the HE-1000 to the SR-009 at the SF Head-Fi meetup at the HeadAmp table. Both very different presentations but overall sound quality they seemed on par and both obviously TOTL. In fact it was what got me to order and try the HE-1000 so I could spend more time with it at home. I was very impressed. My summary so far is for the music I listen to, mostly electronic of all types the HE-1000 fits what I'm looking for over all the TOTL headphones I've tried.