Hi, James.
It's your song to do with what you want.

It was a fun project. I haven't really done anything so "musical theatre" before, and I think the result makes it easier for people to hear what the song could be.
For vocals, obviously real vocals are going to be far beyond what synthetic vocals can give. But I suspect that even the female vocals using the free version of
SynthV will give a better presentation that Emvoice will. There are currently no free English male voices for
SynthV, but there apparently will be a "lite" version of "Asterian" voice in the near future.
As for the mix... every mix has specific goals. For mine, I wanted to create a sense of movement while still keeping the original instrumentation. That mostly involved using gain faders and some low-level edits on the drums.
The rest of it - the balance between the instruments, how much and what sort of effects to use - is subjective. You've heard my suggestions. On another day, I might make different choices.
Thanks for letting me work on this!