Hmm altering the essential nature with fertility magic... this sounds cool...
I always wanted my army of 1000 gifted half-giants with immunity to iron. 
Too bad you had to experiment and now they all also have the flaw: Obsessed (Destroying the Order of Hermes). 
And somebody taught them all Parma Magica as well.
Luckily they are all Criamon. 
with Affinity (Enigmatic Wisdom) and Twilight Prone
Path of Strife. 'nuf said. Destroying the Order is an Apt Thing.
That might prove difficult not just in terms of getting vis to fuel 1000 rituals but also in terms of researching 1000 rituals to cast. (Getting 1000 mothers to that will submit to being ritualed seems challenging as well but somewhat less so)
I suppose you only have at most 9 months to research that ritual, right? 
Nonetheless, the potential of fertility magic to revolutionize the Order is great: I need the check the details, but according to the general idea, suddelty, the magi have the potential to magically engineer "designer apprentices" babies with the Gift and all the nice Hermetic ans Supernatural Virtues they fancy. I would expect that integration of fertility lore in hermetic magic would grant it at least a modicum of replicability, so I would expect not expect the need to research wholly different rituals to produce the the same results in different childs ? What about lab texts of the rituals ?
But then again, there is plenty of hinted ancient secrets that could truly revolutionize the Order, such as doing away with the Limit of Creation with hyperborean secrets, or the Limit of Arcane Connection with defixiones, coordinates or adamite language.
This might be fantastically wrong so don't take it too seriously
I believe that you can reuse a ritual once the original beneficiary has died. This leads me to conclude that you can premptivly research a ritual to have on hand for when an opportunity presents itself.
I am looking more and more forward to the post bringing me my copy - I've been 'patroling' my frontdoor all day and had several suprises, being confused everytime anyone but the post rang on the doorphone 
Still not having seen Ancient Magic yet, I have the thought that it is a great sourcebook, but maybe not something where you want pour it all into your saga. Partly because if all incorporated they would tremendously change the setting, but also because I think it would somewhat lessen the mystery and majesty of each of these if you did. I am mostly looking forward to reading it for great inspiration, and then ponder which of the ancient traditions might make an interesting focus as a plot or metaplot and then stick to that and explore said tradition to its full story and plot potential.
EDIT: And a heartfelt thank you to Erik for seeing to our spoiler urge amidst sessions with his troupe and his dentist! Even if I hope to have it soon, it was great to placate the urges a bit!
That is definitely the intention of the book. Any one chapter can form the basis for an entire saga. Incorporating the ancient mysteries of different forms of magic requires a huge expenditure of time and resources on the part of the magus doing the investigation and lab work. It would be very difficult for a magus to make one such discovery and have it incorporated into the magic of the Order, let alone two -- and definitely not all.
And also the intention I presumed it to have - but some of the fears toward its effect seemed to rest on an opposite approach.
I also think that you might add, depending on YMMV, that beside the rule mechanics alone that something mysterious and ancient in itself deserve more attention then just in passing or as a row of breakthroughs. That whatever you fall for of those mysteries, that it deserves to be used on a larger scale in the plot(s) of a sage, and that this should discourage forcing several of them into the frame of one saga.
I understand what you're saying. OTOH, all of this material hints to be so cool and inspiring that I' probably incorporate all of them - as legends and rumours in the background, as nothing else. A saga might touch one of them, or two, or three, but they would all belong in the lore of the
order, and exist, out thre someplace.
Absolutely amazing!!
I just recieved my copies of C&G and Ancient Magic! YEAH!!
And it arrived after less than 2½ day after I ordered it! And no cross-Atlantic import paperwork or fees either!!!
Those of us who live in 3rd World countries are not so lucky. 
You poor antipodean 
- I vividly recall how I had to await the long transports from the US before I found the FLGS only a few countries away (ignoring the inept ones in my own town - how can you not carry Ars Magica?)
The local FLGS (i have tried 03 different ones , including the one i have been loyal to for over 20 years) ,
seem unable to get Ars Magica any faster than Amazon US.
In fact they are slower , and their overseas supplier unable to ship in-print Ars Magica books at the same time.
One store in Melbourne (a mere 1000km away) seems to be able to get new Ars Magica product ,
but it is more expensive to order within the country , than from overseas.
I'm happy for you lucky bastard It seems I'm going to pay yet again for the notorious efficiency differences between the postal services of Denmark and Italy 
Of course, you know you are now honor-bound to spoil AnM till your fingers catch fire, to mend my wound.
Yeah, I have to navigate ordering from abroad (bc Denmark is expensive) and ordering from withing the EU bc the common market disallow toll fees.
ROFL. Well it was my 30th birthday yesterday, so the postal services might have upped themselves, though they are quite dependable. I did however only get part of my order from London, still awaiting a board game, but apparantly they shipped them seperatly which is probably why the books arrived so soon.
I'll try to honour that... as soon as I get the time to read it. 