Would have better than "Sub Rosa", that's for damn sure!They did.It's a shame the writers never thought of this.
During TNG's run, Starlog did an interview with some TNG writers where they talked about trying to do a mirror universe episode. They said the basic of the episode would be that Spock took Kirk's advice, and we were going to see the inplications. For whatever reason, they ended up not doing it (and wouldn't have discussed it with Starlog had they any intention of doing it). This was around TNG season four or five. I was surprised when DS9 eventually did it.