First of all in general Aeon Closed have a better tuning and frequency response in comparison to the Opens.
There are the RT ones and the Drop Aeon X both open and closed.
It looks like @Resolve doesn’t recommend nor one nor the others.
Essentially the Aeon 2 open and closed and the Noire have a different placement of the magnets in comparison to RT/X: second generation Aeon have the magnets behind the driver and this brings to a better sound.
The Noire are Aeon 2 Closed retuned and with perforated pads.
It is nearly a year that I have and use the Noire and I’m very happy with them.
Consider they are very amp picky and that I love them using my @ampsandsound Mogwai OG as geadamp. I don’t love them very much out of Asgard 3 or other solid state amps I own.
I believe the better saving for you is buying the Noire or keep on saving for the Stealth.
Check also DMS review of the Aeon Open X for a different opinion about them.
PS. I link you the discussion about Aeon X in the forum: