Mad Scientist: I do accept that I have confused Vr and Vref, but this further illustrates why not to ask tech questions on an open forum.
"V1 may or may not be a function of the accel-stop performance; it depends on the aircraft and the conditions, as do issues of whether Vmc or Vmu are limiting for determining takeoff speeds."
Irrelevant, you cannot sum up V1 in these terms, "Vmc" ? Is it Vmca or Vmcg that you are alluding to?
Vmu is not I repeat not considered when determining take off speeds on a balanced field.