After some quality time with the Elear, I'd say I agree to a lot of what you say.
But I'd say lower mids are fuller on the Elear, upper mids are more foward on the Vega (yes, we agree Vega is brighter) which makes for a warmer and more relaxed presentation (although in absolute terms I wouldn't categorize it as relaxed given its dynamics
).
I understand your appreciation of soundstage and that was my initial impression too. But after dozens of hours on the Elear I would differ on how much wider, taller and deeper the Elear is compared to the Vega. For the record, I am also an IEM guy they do get the most of my listening time but there is something to be said for full sized headphones especially open backed.
I would say the Elear has a very similar approach to soundstage and tuning as the Vega (highly coherent and yes less airy or big than others in their category) but the stage size is indeed much bigger and that applies to depth as well.
I have listened so much to IEMs these past years (3/4th of my listening time) that I might have forgot what full size open back bring to the table.
Yes, the Vega hit harder but that also because there is quite a bit of pressure applied to the ear (as closed as it can get). And again, the Elear don't sound like open back bass wise, they really kick! Same goes for the perceived resolution nothing between you and the music (well, a few millimeters), the Vega also provide Ginzu knife layering with a precision like nothing I have heard.
Yet, as I get to spend some time with the Elear I am re-discovering some advantages of full sized open back and one of the biggest one is "realism". With the Elear I feel like I am litterally at the concert venue, it's not a big stadium like but rather one of those smaller concert venue I love so much where you're close to the artist. The music is breathing, decay feels more natural, there is more space between instruments although the relative space is very similar to the Vega so all in all my brain will interpret soundstage as being close to the Elear.
I feel like with the Elear despite loosing on layering and depth vs the Vega, it takes less effort (or at least from listening fatigue I deduct it does). It's like the contours of instruments is not as sharp but the distance between them is greater. This makes for a more relaxed experience. I don't know if I make sense.
This is my experience with DX200 on high gain balanced with both.