Ovarwa, much of what you say is true and a I agree in principle. Only comments i would make are the following:
with cthonic magic, it has been brought to my attention just today offboards that in order to use this virtue as a focus for higher casting total the character would have to be committing an act he/she knows is evil which is truly inviting infernal attention and taint. Not the best choice compared to a neutral focus (major or minor).
and..
Flawless magic does not grant the ability to cast without words or gestures, it merely gives you a starting 1 in mastery of new spells. Granted a character could take either subtle or 1x quiet magic as a mastery skill but completely silent and still casting would require two more mastery levels for each spell. having a character with that Major Virtue in table top play i can say that it is truly an overrated virtue in the long run. I would much rather have the combo I suggested if multiple MVs were permissable AND if i was playing a damage dealer magi.
Skilled Parens is also nice for char gen points but in the long run it is isnt as useful as many other virtues that keep on giving during play. Cyclical Magic, Deft Form or Potent Magic are much more continuously useful virtues.