I've just received a copy of At Home Abroad, Mark Twain in Australasia,
by Miriam Jones Shillingsburg.  In the preface she quotes Dennis
Welland, thus: "[the American editor was] so unscrupulous in the textual
changes he took it upon himself to make, that there is every reason to
adopt More Tramps Abroad as the authentic and authorized text of this
work, and Following the Equator as an abridged variant of it."

I have The Oxford Mark Twain edition.  I am also very new at looking at
this book but had not heard this criticism previously.  I'm wondering if
any Twain-L people might comment on this.  I've just begun recording my
narrations of this book and mapping relevant locations.