I have mentioned the above a few times but finally I can provide a reference.
Do bear in mind that the term 'superagonist' does not automatically make a compound highly potent. There is research suggesting that both tianeptine and tapentadol may also be superagonists. It's not a topic that has been well explored so forgive me if I can only offer tacit insights.
What I foresee as a possible issue is that traditional substitution therapy may be of less value in treating the AWS encountered when people swap from a superagonist to an agonist.
While not of statistical value, the first case of clandestine etonitazene production/consumption was in the 1980s and was a single chemist at Morton-Thiokol. I do remember it being in the news because the chemist had broken 'rule 1' and accounts by his co-workers suggested he had dissolved his product in dH2O and was self-administering it nasally. Apparently he was consuming a dose on a 20 minute schedule. He was apparently provided with large doses of methadone but for whatever reasons took his own life before the legal process could be undertaken.
I was also briefly in communication with 'Robojunkie' who, along with 'Superjunkie' (the latter being a chemistry student) were making and consuming fentanyl derivatives. They to ended up on a 20 minute dose schedule and the former remarked that in spite of being provided with copious quantities of potent agonists still suffered acute symptoms for over a year. I've also read other chemists stories concerning their consumption of fentanyl and the fact that substitution wasn't very helpful.
I will conclude by remarking that although phenapromide derivatives are nowhere nearly as explored as fentanyl derivatives, the two classes appear to be subject to a similar QSAR which in theory would provide for hundreds if not thousands of analogues. If I had to guess, I would expect this to be the next class of highly potent opioids to arrive on the black market. I'm not sure if a test for this class exists but it's entirely possible that they have already reached the market but have yet to be identified. So please be careful out there.
