Hey Van,
The variation you mention has nothing to do with the "if it were not so" question of the OP. That question is entirely translational and not textual.
The textual question you bring up has to do with the following clause in that verse (John 14:2):
Most manuscripts (around 1600):
... I would have told you. I go to prepare a place for you.
OR (translational preference)
... I would have told you, "I go to prepare a place for you."
OR (translational preference)
... would I have told you, "I go to prepare a place for you?"
A few manuscripts (around 25):
... I would have told you. For I go to prepare a place for you.
OR (translational preference)
... I would have told you that I go to prepare a place for you.
OR (translational preference)
... I would have told you, "I go to prepare a place for you."
OR (translational preference)
... would I have told you that I go to prepare a place for you?
OR (translational preference)
... would I have told you, "I go to prepare a place for you?"
First of all, this is making a mountain out of a molehill. Why? Because the translational options with or without the οτι are basically identical.
Second, the presence of οτι after verbs of speaking is extremely common, and this in itself could have induced a few scribes to add it here with a view to the most common form of syntax. (This is a very basic observation of textual criticism.)
Third, a minority of scribes at any given place may either add or delete such instances of οτι. See
this blog post where I have culled many such instances from the Gospel of Matthew.
Fourth, the οτι is not present in the earliest manuscript, p66. This manuscript is 125–150 years earlier than the earliest manuscript that adds οτι. This shows not only that the reading of most manuscripts was present 125–150 years earlier than the earliest Alexandrian manuscripts that add it, but also that later on there was an active attempt to correct the text away from the Byzantine reading and toward the Alexandrian reading (observed in the later correction of p66 to include the οτι).
Fifth, the earliest writer, Origen (before 250), who predates the earliest Alexandrian witness for the addition of οτι by 100 years, also agrees with the vast majority of witnesses and does not have it.
This is not to say that the reading of the majority of witnesses should be accepted simply because it is also the earliest attested reading in both the Greek manuscript tradition and the church fathers. What it does demonstrate, however, is the rather hypocritical, or at least uncritical, use of a manuscript's or father's age simply to argue for your preferred reading
when it suits your fancy.
Since you blatantly reject the earliest attested reading here, I will therefore take this as
your tacit admission of the impotence of the argument that the earliest attested reading is inherently better, and further in the future I will reject your arguing this as any qualitative criterion to arrive the original text.
Now the translational preference for the question ("would I have told you that I go to prepare a place for you?") is somewhat problematic in that Jesus hadn't yet told them that he was going to prepare a place for them! Why do so? Why not choose from one of the many other valid options?