First of all, I have no issue with the Terran Empire types being in Starfleet uniforms as:
A) They're infiltrating as Starfleet.

The mirror seems to be a closer reflection since DS9.
That said, two things:
A) When they're not infiltrating, they ought to have the TE combadge.

Klingons are really out of place as TE officers.
Beyond that, I always kinda wanted to see a second mirror universe that was more good, pacifist. No wars. Earth and Vulcan just... met in the middle. Even more Utopian than standard Trek. Uniform variants, etc. And then have someone from that Universe come to ours and, on the verge of snapping, set out to change everything the way Kirk did with Mirror Spock. Like some admiral that gets swapped out for his "even more good" counterpart in a transporter accident and starts pushing total pacifism. Like some Starbase gets wiped out because he orders them not to fight back.
I think an Admiral like that could make a compelling villain and deal with some of the necessary darkness of the STO setting.
Comments
Mirror Self
Undine Infiltrator
Whos who? :O
I don't like the idea of a good mirror universe. Where would be the fun in that? And no admiral can order people not to fight back. If he tried security would escort him to sickbay. Sure, he could sabotage the defense grid, but that would be murder. And why would a completely pacifist universe have a Starfleet anyway? Why would they have weapons?
Agreed on the uniforms.
What I was picturing was...
You know how Kirk persuaded Mirror Spock to change things and it eventually created a more nightmarish scenario? You ever read the comic JLA: EARTH 2 where the Justice League tries to liberate and reform a twisted alternate earth and everything they do just makes things worse?
Picture that from the other side. Someone from a better universe shows up in ours but their solutions keep making things worse. So they go mad at how terrible our universe is and eventually say: