As a mostly non-practicing, lifelong Mormon, I find most of your conclusions here reasonable. And I commend you for the open-mindedness required to look into a

As a mostly non-practicing, lifelong Mormon, I find most of your conclusions here reasonable. And I commend you for the open-mindedness required to look into a widely-maligned minority religion like Mormonism. I would say, though, that the idea that more manuscripts necessarily implies a more reliable textual history is incorrect. The textual history of the Book of Mormon is incredibly simple, substantial parts of the original manuscript and the entirety of the printer's manuscript (a copy made of the original for purposes of printing it) both exist. For the New Testament there are no "autograph" manuscripts (original manuscripts) and the earliest manuscripts are at best a century after the originals. Reconstruction based on all of the numerous NT manuscripts really only serves to get you back to the point the the BoM text is already at, and not even quite there. See Royal Skousen's Book of Mormon Critical Text Project for more on this. It took hundreds of years for trinitarianism to be adopted as a consensus, and prior to (and also after) the great creeds there was substantial disagreement about the nature of God. I wouldn't put too much stock in them as a doctrinal buttress. See "Voting About God" by Ramsey MacMullen. Again, kudos for all your research into Mormonism, which I find to be a fascinating tradition, even if I now seriously question its truth claims.