Hi Elliott.
This thread is a great idea.
I do almost exactly the same as you with just a couple of exceptions.
I've been using Groups to keep identical sections together (for example a chorus). Then, when I make a change in any member of that group, it's updated throughout all instances of the group. Groups also allow me to change tone and most other performance characteristics, too, and they are isolated to that group. I must say, though, I like you idea of having individual sections in their own Synth V file.
Like you, I much prefer using the stand-alone version of Synth V for working with. Once I get the vocals sounding as good as possible in the stand-alone version, I then open the file as a VST plugin so that I can make minor changes on the run.
Lastly, I use volume envelopes in my DAW to shape the Synth V vocals so that they reflect how I would sing the vocal line. This is important because prepositions and conjunctions are usually significantly quieter than verbs and nouns, and Synth V doesn't always get the volume relationship between syllables as accurate as it should be. These are tips that I picked up from Pat Pattison when I studied prosody with him, and matching syllabic strength with appropriate locations within the bar.
The attached image shows how I've volume-shaped the phrase "A friendly shimmering sun" for Natalie in Reaper. This is from the song "Every Single Day" (the link is below).
Regards,
--Noel
• my latest song: Every Single Day (a duet with Kevin & Natalie, Synth V vocaloids)