I looked at your responses to MBL and find them inconclusive.
Incidentally, you clearly inferred that this is a one-shot ability when you said "I'd prefer to hold on to my ability" and I think you and we are better off without it.
First, I don't like you having a veto power to bring one day to night over the other players wishes at a time of your own choosing. I don't think your individual wisdom exceeds the collective wisdom of the town, with apologies to Ultima.
Second since it is one shot and since Erg0 is obvscum you have an opportunity to divest yourself of this power and thereby become a vanilla townie. That will take a target off your head. And, to reiterate, I think your analytical skills are worth more than this particular power role.
Finally, I think our collective instincts about Erg0 are right. Your instincts may be wrong later and you would end up killing yourself on our behalf. Or alternatively your fear of being wrong will leave you holding a power that you don't want to use while at the same time it is a power that scum will want to divest you of because of its unpredictable nature. Thereby forcing you to sit under a sword of Damocles for the rest of the game.
It's my best advice.