I was wondering about this because of the order I'm going to play them in. I'm doing a kind of Herma Mora-oriented playthrough and I'd hate for Mora to introduce himself to me in Septimus Signus' Outpost after I've already become his champion in Apocrypha. However, I'd prefer going to Solstheim now and doing Discerning the Transmundane later if his dialogue in the Outpost does change. I know he references Discerning the Transmundane once you've entered Apocrypha, I'm wondering if it also works the other way around.
Any thoughts? (: