I'll point out that you said here it was the best virtue in the game.
While best and most powerful are arguable as to their equivalence, you're love of Flawless Magic was professed early here in the forum, and I think in our conversations, often. 
Like I said earlier, the virtue seems to magnify other things about the magus, and there are some virtues that are really complementary to a magus with Flawless MAgic. At gauntlet it's Mastered Spells, maybe even well past gauntlet, because it's worth effectively 100 XP. Cautious Socerer further reduces the botch dice, and with a mastered spell they're taking 4 botch dice off every roll, and in many cases this means they will roll no botch dice.