Sorry, I was mostly referring to the upper treble. You can see that the HE1000SE has a massive upper treble spike, just above 10kHz. This will make the SE’s more “sparkly,” but more fatiguing.

I use my HE1000 Stealth everyday and I don’t find it to be sibilant. However, I have tinnitus, so take my treble impressions with a grain of salt. You mentioned that you wanted better soundstage and imaging, and the HE1000 Stealth is phenomenal for that. It goes for a decent size soundstage, while keeping the imaging precise. I can tell exactly where each instrument is. This is unlike some headphones that go even further with their soundstage, but end up with less precise/more diffuse imaging. Combine that with its excellent timbre and detail makes everything sound so lifelike (at least for headphones).

The HE1000SE measures with much higher treble. Oratory1990 has measured both, and I trust his measurements a lot; he is very experienced and uses high end measuring gear.

HE1000SE Frequency Response Graph

HE1000 Stealth Frequency Response