I voted yes for that mission for two reasons. The first was, as Rein said, because from my perspective, it was the most likely to go through, and if that had gone through, then it would have been an easy win. The second was that if it had failed, I would then be able to narrow it down to 1 out of 2 people to being one of the spies. Since I know that I am not a spy, I know either Rein or Elieson must be.
Now, I propose that whether we choose Mission 3 or 4, we should use the In the Spotlight card on one of the people in the mission, the one we find most suspicious. Most likely 1 of the 3 people in Mission 2. No one with that card on them would sabotage the mission, because then we'd know that they're a spy. So if it still fails, someone else on that team must be the second spy.
We could save our card to finish it off, but in the case that the next mission fails, it becomes useless because even if we pick a spy to reveal their mission card beforehand, we'd lose anyways.