Before I answer that, you've gotta know something about me, in the fact have much time to sit down and listen to my home set up as it is not convenient for me. I do most of my listening on a 'portable' setting/setup. So the Stellia, when I first saw the announcement on HeadFi TV, I was like "I have got to get my hands on these". Because I have always been looking for an end game closed back headphone. back in 2011 when the T5p came out I got one immediately - it was flawed, bass was boxy treble was sharp but had no extension and refinement. When the HD820 came out I had high hopes on that too.... buts to me it really did not sound that good (coming from having an Utopia. Wasn't great at all. And when I saw the video I knew that the Stellia would not sound the same as the Utopia, but I'd settle for a 'Utopia-level-sound' in a closed back configuration. And man did it live up top my expectations. Furthurmore, the Stellia is SO SO SO easy to drive, and to me sounds better out from my 1Z than it does on my Hugo 2 - more warm, more musical and more enjoyable.
So now the HE1000 vs Stellia, I think you'd know my answer, definately wouyld reach for the Stellia more and use the Stellia more based on the above. With the HE1000, I'd have to at least use it with the Hugo 2, and its an open back - not so ideal in my usage scenarios. Hope that helps and hope that you do understand that my answer is based on my usage scenarios and preferences.
Side note:
Listening to the Utopia and the Stellia at a private hire office space with some very fine cables from DHC Cables. Its a Beryllium partyy!