I discovered today that the Letters of John Wesley that appear in volumes 11-13 of the Works of John Wesley aren't complete. Even worse, it appears that the letters have been edited very heavily, not just omitting words, but changing them.
For example, I've just been looking up one particular letter. The Logos edition has:
But, doubtless, what you mention is a point of the last importance, and deserves our most serious consideration: The rather, because the strange account given of it by some has induced others to deny the doctrine of atonement; although this is the distinguishing point between Deism and Christianity.
Whereas a later edition has:
But certainly the subject is of the last importance, and deserves our most serious consideration. Indeed, nothing in the Christian system is of greater consequence than the doctrine of Atonement. It is properly the distinguishing point between Deism and Christianity.
That's a significant difference in meaning!
We need the full eight volumes of letters published by Epworth Press in 1931. That's the edition that's cited in the scholarly literature.