Oh,
If you do go down the MM road, I heartily recommend a virtue like Cautious with Artes Liberales. Great for removing the last 2 botch dice from unmastered rituals. Mythic Stamina is a good alternative, though some GMs will balk.
MM+Cautious(AL)+Cautious Sorcerer reduces rituals by 5 botch dice, potentially to 0 (for rituals level 40 and under.) This magus really wants a familiar. Other magi can take the same botch reducers, but the MM can cast those big rituals without risk, and huge rituals with low risk. That can be huge. (MM provides power and safety at the cost of versatility; LLSM and DM provide versatility at the cost of safety. Note that DM does nothing to improve the safety of spont/2 spells; botches and Warping are possible whenever DM is used.)
If he is a generalist, then virtues to enhance AL, Phil and MT might be nice. But there aren't enough points to make all that work well, either virtue points or xps. Verditius magi benefit more from Phil than AL. An applicable faerie correspondence adds to Phil, AL, Penetration and a possible Mastery Ability!!!!! (For anyone counting, the correspondence is added thrice to the casting total and once or twice to Penetration.) Any ritual or ceremonial caster can benefit from this, though a Mercurian is more likely in a position to churn out rituals.
Hermetic Choreography speeds up ritual casting, though not by enough to make the virtue shine. Not bad but not great. Ceremonial casters like it more, I think. Either way, these spells are still cast out of combat, when there is a good span of time. Now if it were 1 round/magnitude, yeah.
So MM+Cautious(AL)+Cautious Sorcerer+SFB+HC.... That's a ritual magician to be respected. 1 or 4 more virtue points plus a free minor virtue: Strong Parens? Book Learner? Cyclic Magic? Performance Magic? A minor focus? And this guy's sponts might take a little while, but the faerie correspondence might add twice to the casting score. Or ditch SFB and the correspondence and recoup 3 virtue points.
(The Schism War was ended by a handful of Merinita Mercurians who killed off all of House Diedne using Symbol Magic. They never left their covenant and didn't need ACs. Mercurian Magic + Folk Magic + Symbol + Bloodline... ftw. And no one in the Order has a clue, even to this day.)
I'm impatient, so MM isn't an easy virtue for me to use. But over the long haul, this is a very powerful virtue. Admittedly, most sagas don't last very long.
Anyway,
Ken