[split] Does Voynichese evolve from A to B?

[npcompl33t]

The reforms were generally dozens of independent changes; but doing them all at once was much less disruptive and confusing than doing them one at a time.

I imagine that the VMS Author could have decided for a general spelling reform for the same motives; and chose to do all the changes at once for the same reason.

Are you familiar with the black book of basingwerk? My understanding is that it represents something close to  the type of 'spelling reform' you are discussing within a single book, so also relevant to your and @nablator's discussion. The book undergoes a sudden, abrupt change in spelling. The first five quires of the book are written by an unknown scribe in a conservative Welsh style, while the remainder of the book was written by the famous Welsh poet Gutun Owain, who writes in a style that would have been more contemporary. He introduces late medieval spellings, variable phonetic interpretations of consonants, etc. 

It sounds like this is exactly like your hypothesis. Part of the book is written in a conservative style, and the remainder is written in a style that incorporates something like a 'spelling reform'.

Here is the MDS plot of that book compared to voynich.

   

I know that you disagree the points on the right create a continuous path. But surely you can see the difference between these two plots, right?

As for dialect change: it is unlikely that the VMS records knowledge that the Author acquired directly.  The breadth of the topics argues against it.  Most if not all of the contents must have come from pre-existing books, or verbally from informers or teachers. 

So under this theory, you are saying that it is possible the content came from pre-existing books written at different times, or in different dialects, and the author assembled them with out any kind of normalization into the MS?