I thought the hd800 sounded better than a sr009 from 2 different totl amps. This is an hd800 running on a bottlehead crack..
So if this he1000 is league(s) above the hd800, which according to many it is, then in my scale the stax is a bad buy. Just my thoughts of course.
I think this is a bit subjective, and depends on the kind of music you mainly listen to. For me, a Stax SR-507 sounded preferable to the HD800, especially because the realism of wind instruments. The SR-007 Mk1, the Sigma, the SR-009, and the SR-Omega are all better than the SR-507. Yet there was a member who preferred the 507 over the 009, especially for the price... But that personal choice doesn't make the 507 better in general. Also, the 007 and the 009 can be also very positively modded (see http://www.head-fi.org/t/754839/stax-sr-009-and-sr-007-mk1-earpad-diy-mods ), and the result IMHO is better than the Anaxilus modded HD800 (http://www.innerfidelity.com/content/diy-modification-sennheiser-hd-800-anaxilus-mod ). Of course, YMMV. But there are music genres on which I prefer my modded Fostex TH900 over all my Stax. So what, that alone doesn't make it a better headphone. And none of the Audeze was for me, though the LCD-3 is really fine. These are all subjective, and it's so easy to generalize.
It is not hard to imagine that the HE1000 has the potential to play in the league of the top Stax and even beat them in some respects, and also beat the HD800. But it is hard to imagine it will beat them on all respects. So I expect it will come down to personal preferences again. Perhaps there will be ones preferring the HE-560, especially for the price. We'll know more in a couple of months.