Hi DM
However, I would not call the Jewish step to monotheism 'unique'. Atenism was definately earlier under Amenhotep IV, and has the same development of polytheism-henotheism-monotheism (eg hymn of Aten: O sole god, like whom there is no other! - unfortunately I can't read ancient egyptian to check this translation, but this seems reasonable from what I've read about Atenism). IF the Jews were influenced by this (like Freud speculates in Der mann Moses und die monotheistische Religion), We should also say Judaism appropriated an already established pattern. IF this was not the case, however, we have your example of an exact repetition of development of poly-,heno-,monotheism in Egypt and Israel.I'll leave Zoroastrianism out for the moment because its dualism tends to give me headaches :)
The main difference, I feel, is that the relationship between Aton/Atum henotheism (which I think never reached the stage of monotheism proper) and Judaism is never explicitly claimed by the latter. Monotheistic Judaism doesn't pay any tribute to Akhenaton (as Christianity does to Judaism and Islam to both). Neither is Akhenaton claimed as an anonymous Yhwh worshipper like Abraham is claimed as a true believer by the new standards of both Paul and Muhammad (!). Some influence is undeniable (cf. the Hymn to Aton and Psalm 104) but it remains essentially on a literary level. The Jewish shift to henotheism in Deuteronomy rather reflects and reacts to Assyrian influence (Yhwh as the exclusive suzerain, like and instead of the Mesopotamian rulers), and the next step to monotheism in Deutero-Isaiah seems to also reflect and react to Persian influence (Yhwh as the only source of both light and darkness, good and evil, un/like Ahura-Mazda). So it seems that the long past Akhenaton episode had little room in the actual making of Jewish monotheism, even though it could later be read back as a kind of praeparatio mosaica.
I should also add that the model of appropriation of "the faith of ancestors" suits the historically dominant posture in both Christianity and Islam (with an essential difference re: writing, since mainstream Christianity appropriates Jewish scripture while mainstream Islam rejects Jewish and Christian scripture as falsified) -- but it is not necessarily universal in either. I don't know much about the early theologies in Islam, but there were distinct radically anti-Jewish currents in early Hellenistic Christianity (as reflected in the discourse of Stephen in Acts 7, where the Israelite worship is described as idolatrous right from the start). Cf. also the ultra-Paulinism of Marcion which rejects the OT.