How much work to write an enciphered manuscript v one with complex meaningless text?

[MarcoP]

I just doubt that there would have necessarily been more work involved with producing a manuscript like the Voynich using a simple substitution cipher copying from an existing text than producing complexly structured nonsense text of the kind found in the Voynich.

I agree: the effort should be more or less the same. Just about the same effort as writing a manuscript in your everyday language with your everyday alphabet.