That is something I’ve been doing for a while now.
Of course, that isn’t entirely a correct statement on your part as Ethereals aren’t exactly the same. Sure, they do have Void in their background in terms of the Void attacking their home world. However, Void Elves have the added benefit of Void actually being apart of them which is an additional cool factor.
Additionally, full on Void Ethereals wouldn’t really make total sense as those have consistently been apart of the evil Ethereal faction.