Jacob, I hope someone with a more encyclopedic grasp will weigh in, but my thoughts are these.
1. There is a big difference between Pseudo-Dionysius and some of his antecedents and successors, Greek and Latin.
2. I think Harnack locates the dividing line between truth and error in the wrong place. There were errors imported from the Greek world, sure; but there were errors imported from the world of Hebrew thought as well (e.g., Ebionites). The Hebrews were not always faithful to their Scriptures (neither the Sadducees nor the Pharisees), and the Greeks and Romans were not always wrong. Gnostic influences were pretty clearly noxious, but it's also pretty clear that the Creeds are anti-gnostic.
3. I am unconvinced that the decline of the doctrine of an empyrean heaven has been for the health and strength of the church. After the Reformation scorned Pseudo-Dionysius, and returned to a contextual rather than sentential reading of Scripture, the idea of an empyrean heaven still persisted. I find it alive and well in Durham; there's an idea in Fairbairn about the value of material works persisting into the new creation which might tend to de-emphasize it, but I'm not sure about that.
4. The early and medieval church tended to be pretty hilarious on marriage, from Augustine's wondering if it were not for procreation how a woman could ever be a more suitable companion for Adam than another man, to Hincmar's permission of a separation for those whose sorcery-induced sterility could not be overcome with exorcism and ecclesiastical discipline. It's good that at points (such as on second marriages) they tried to restrain themselves within the bounds of Scripture, not prohibiting them though it went against their instincts; and it is rather beautiful to see that they opposed the infamous double standard which has marred a lot of cultural Christianity since their time. But we have sometimes gone too far in the opposite direction from them, to the point where Paul's commendation of the single state and of not giving in marriage feels embarrassing or has to be confined to particular circumstances. A similar movement, switching topics to the active vs. contemplative life, has taken place as our bourgeois ideals have carried us to the point where sermons on Mary and Martha often wind up justifying Martha and making her a good example rather than focusing on the one thing needful.