I have no experience with Stealth or Lyr+, but I’ve had Expanse since June and Ether 2 for many years — actually wore out the original stock pads.
Overall, I’d say Expanse and E2 are close relatives. E2 is less refined, and has some roll-off at the highest frequencies. This is the most noticeable difference, and it’s pretty obvious in a direct A/B comparison. I would call Expanse somewhat more linear/referency. Sub-bass might come through a bit more from E2, but that could also be an artifact of E2’s more subdued treble.
Expanse headstage is a bit more open/3d and also somewhat more precise (which finding surprised me as I’ve always admired the E2 stage/image).
That said, I enjoy my E2 very much, and they’ve always been my ‘nighttime/in bed listen’.
So, bottom line, I do hear Expanse as an upgrade, but certainly not a ‘night-and-day’ improvement. On the other hand, if your biggest criticism of the E2 is the highs, then Expanse will be a worthy upgrade.
Also, while Expanse isn’t uber-light like the E2, I do find them very comfortable.