In short, Bravo! Bravissimo!
I do have disagreements when it comes to some of the opinions V expresses: no surprise here, since I've raised most of them before here or by e-mail. For right now I'll just address the issue of the 'theory of transmission.', since that in the narrower context of the Akallabêth was actually the topic of my maiden HoF posting!
It seems to me very clear indeed that the 'frame' or 'transmission theory' went through dramatic changes in Tolkien's later life, and that these were marked phases, one replacing the other in succession. The first and by far the oldest of these was Aelfwine story, which was still alive and well in the early 1950's, and a part of the text of Ainulindalë and Akallabêth etc. However I think it demonstrable that the Anglo-Saxon connection which dated from the Lost Tales had been decidedly rejected by the late 1950's. It simply can't be consistent with the next phase, the 'Númenórean vector'. In this stage, associated with the late revisions and the Myths Transformed etc, Tolkien saw the Sil material as having been garbled, filtered through and blended with Mannish myths and misperceptions and so passed down to us- and this simply couldn't be squared with the Lore of Eressëa, where Pengolodh would have transmitted the untainted Elvish 'truth.' The one replaced the other, and couldn't have coexisted in the same volume.
But the Númenórean vector was not the last word on the subject, either; although we're used to thinking of Tiolkien's major work on the story as having ceased about 1960, he never stopped thinking about it, or tinkering with it. I submit that by the mid-1960s it had given way to (or morphed into) the 'Rivendell vector.' Back then
I believe this can be traced. The first hint appears in (probably) the early '60s, with the statement in "The Line of Elros" that Elendil wrote the "Downfall of Númenor, which was preserved in Gondor.". This is of great interest because, as I observed back then, the Akallabêth is explicitly a fusion of the "Elvish" Fall of Númenor and the "Mannish" Downfall of Anadune- it represents in fact the Mannish legend corrected in light of 'true' Elvish lore learned by the Dúnedain. But not, as I supposed then, by Elendil I don't think, or the Gondorian tradition. Elendil would have been the vector for the direct Númenórean version, DA; the corrected version which Tolkien called "Dunedainic" circa 1965 would have to have been connected with the House of Elrond and the remnants of Arnor. Which leads us to...I wrote:This raises the interesting possibility that by the mid-60s Tolkien had evolved a rather subtle view... that the Breaking of the World really *did* happen, but Men are too blind/pragmatic/unimaginative/out-of-touch with the Valar to conceive of such a cataclysmic Divine intervention- so they refused to believe it. In other words, Arda globed from the beginning is an incorrect Mannish myth, concocted because Men keep falling back on, well, scientific method rather than faith and revelation.
The mid-Sixties: There are very, very few writings from this period, but there are two very important statements in this regard. One, which Vor cites, is that according to Dick Plotz Tolkien told him, in 1966, that Bilbo's 'translations from the Elvish' were The Silmarillion. The other, which I don't think Vor picked up on, was the fact that the 'three volumes bound in red leather' were added to the LR text in the Revised Edition of 1965. A third, and illuminating, is the 'Akallabêth wrapper,' which as I have said demonstrates the morphing of the 'Númenórean' vector into an Elvish-Dunedainic vector.
In sum: I think CT was absolutely correct to excise the references to Aelfwine/Pengolodh: these had been decisively superseded in the years following the LR's publication and the concept of the Eressean vector rejected. I think, also, that the 'Númenórean vector' was at least unstable if not rejected completely by Tolkien's last years, and in any case can't be squared with the clear indications of the Rivendell- or Bilbo- vector: The House of Elrond would not have perpetuated garbled Mannish errors!