I was replying to McGrath's post rather than yours, but the vulgar is not entirely lost. Beside my point about the v/w pronounciation being established by reference to puns (and therefore reflecting common rather than literary practice), there are plenty of Latin graffiti of the period that demonstrate demotic usage, those preserved at Pompeii and Herculaneum (mainly in brothels, if I recall correctly) being particularly amusing, if brief.