Who doesn't like the Peregrine class? Heck, I've started a couple of sketches for a design set post-Nemesis, though I have yet to finish them sufficiently enough to the point that I feel they are ready to be posted.
It sounds like that unless you are on top, living in the Terran Empire is only a few steps above living in hell. I would feel sorry for any Federation vessels that accidentally ended up in this version of the Mirror Universe (or any other for that matter).
I have no doubt that Section 31 is well aware of the Federation's universe, and what their version of Starfleet stands for. A fight with a S31 vessel would be vicious, and I wouldn't be surprised if a Starfleet captain that knew who s/he was up against chose to self-destruct his/her vessel rather than surrender if fighting back or running away doesn't pan out.
I think we all know that the Empire doesn't hesitate to use torture for any reason, and considering that the Federation's S31 believes in using desperate measures, the Empire's S31 must be nigh non-negotiable, even if they had a phaser to their head.