I understand where the proponents of the Limited Geography Theory are coming from. I really do. I understand their need to retreat from the traditional hemispheric view of the Book of Mormon people. They're in a tough spot. But, ultimately, I believe this retreat into the Limited Geography Theory is a dead-end.
What is the Church actually based on? The Book of Mormon? No! The real foundation of the Church is Modern Revelation. It seems to me that the primary reason that The Book of Mormon is considered to be the "keystone" of the LDS Church is because it happens to be the focus of Joseph Smith's concept of modern revelation. One of the main functions of the Book of Mormon in the Church is to simply verify Joseph Smith's claims to speak with God. That is the true "keystone" element of the Book of Mormon.
The prophets and apostles throughout the entire history of the Church have been both consistent and constant in their sermons regarding Book of Mormon lands and people. Proponents of the Limited Geography Theory are asking us to discount these words of the past (and present) prophets of the Church.
I have included only a fraction of their statements in this essay, but I now leave it up to the reader to decide the quality of their testimonies, and how easily their words should be brushed off.