For comparison, here's a demo done with Sinsy and BiaB: Words Like Smoke

Compare that to a demo using the Vocaloid AVANNA and BiaB: The Water Is Wide

I've tweaked the syllables a bit in them, but I think they're representative of the sort of sound you can get out of them. Sinsy has a heavy Asian accent - she a lot of trouble with r and th, for example.

They both come off as heavily retuned, because of the nature of the resynthesis. I've also had someone use the word "funny" when hearing it. Neither sounds like a native speaker.

But to see how far vocal synthesis has come, here's 1970's style formant synthesis (my own code): Loch Lomand

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?