Both writers make good points and I cite each of them in my books, but for now I'll just mention one thing.
Roper writes: "Recent scholarship on the question suggests that the only natural phenomenon that could account for all of the events described in chapters 8 through 10 of 3 Nephi would be volcanic activity.Hedges does not dispute the validity of these conclusions, but he questions their relevance to the Cumorah question. The connection is reasonable, however, if the Jaredite and Nephite armies never left their primary centers of settlements near the isthmus. The destruction at the death of Christ enveloped important settlements at both ends of the lands southward and northward, bracketing the region in which these events were witnessed to have occurred. That sphere of destruction included the Amulonite city Jerusalem in the land of Nephi at the southern extremity (see 3 Nephi 9:7), and Jacobugath in “the northernmost part of the land northward” (3 Nephi 7:12). Since Cumorah seems to have been close to or within the land of Desolation in the southern portion of the land northward, that seemingly places it within the destruction zone, even if the hill is not referenced in 3 Nephi. Given these parameters, the suggestion that Cumorah was in a volcanic zone seems reasonable, although it poses a serious problems for the New York correlation."
Roper makes a good point here, but like so many other arguments made by Mesoamericanists, he has it exactly backward. The suggestion that Cumorah was in a volcanic zone is not reasonable: it is preposterous. That theory poses a serious problem for the Mesoamerican correlation.
I've explained why the volcano theory doesn't work at all; the text never mentions volcanoes, the description of the destruction doesn't match volcanic activity, and there is a place in North America where such destruction is not merely theoretical but historically documented.
I spelled this all out in an article that the Interpreter refused to publish, so I might as well blog about that next.