As a big fan of the Omega armor, I had this idea about it.
You can already specify if you want to wear a helmet or not - how about choosing between an open or closed helmet?
The closed one obviously would be the one we already have.
The open one would be the same model, yet with the face showing, while the faceplate is hidden (opened and slid back up into the helmet). Maybe even the jaw part of the helmet disconnected from the rest and slid downwards into the collar part of the armor.
I used my very limited photo-fu to fix you up with this "sketch".
It doesn't look as good because I had to fetch the helmet from another pose, but to show the general idea..
The same thing could be made possible with the MACO helmet, maybe those are visibly a bit more padded when the visor is open, while omega would look more functional.