Few would choose to found a covenant without a Vim/Rego vis source, unless they had formalized trade with a covenant that could supply such. Nobody wants to spend their seasons cranking out vis for the Aegis unless the compensation is particularly high (even then, some players won't want to because their plans need to be uninterrupted). Because sooner or later every magi (almost) has to do this to get the vim vis needed for talismans, familiars, longevity rituals or other enchanted stuff they want to make.
Almost makes me wish you could render down any other vis to Vim vis somehow. Aside from the Redcap network, that is.
Also, if you can get you hands on the 5th ed Covenants book*, that's a wealth of additional material, opens a lot of doors, adds a LOT of color, answers a lot of questions - and adds some (optional) complexity and bookkeeping but as an overall advantage to the PC's. Recommended - altho' if someone in your Troupe is thinking of buying a single book, perhaps not before the 3 Houses books (also very good), as approp for the PC's House. Or maybe so - ymmv.
(* There is also a 3rd ed "Covenants" that is floating out there, that is still nice but VERY diff rules-wise. Not a waste if you can find it (really) cheap, some is still usable and good for inspiration - just be aware of the diff. The covers of all 5th ed books have that similar look. 5th ed Covenants: atlas-games.com/product_tables/AG0280.php )
Re-read the description of the seasons of the Covenants (68-70). A true "Winter" covenant has declined considerably, and is often seen on a par with a Spring Covenant, with different headaches but just as many (and often bigger ones).
Then re-read the the insert on page 72. 825 build pts is an "early Summer" covenant. Now, given the drop from 2000 ("a weak Autumn") to Winter (200) maybe a Covenant on the slide down. Nothing wrong with a higher-powered campaign, but be aware that this is not the "kiddies' wading pool" depth.
In the vein of good supplements to pick up after the main text, Covenants, and the Houses of Hermes books are all excellent choices. And I personally prefer the PDF versions (searching the PDF for the win), and they are about 1/2 the paper price. They are DRM free, too.
Maybe you should think about which Boons/Hooks are obvious or likely to be chosen, to help the players get an overview and decide. In the setup of a Winter covenant is decided upon, some Boons/Hooks are more likely than others.
Personally, I belong the the group wanting Aegis to need Penetration.
First, there are no rules saying it does not. Yes, Aegis is said to not mesh perfectly with Hermetic theory, but this does not need to mean it is excluded from normal rules. And all directly affecting spells, Wards included, are ruled to be Resisted.
Second, Aegis is better than a Rego Vim ward, since it does not only keep beings of Might outside, it also reduces Casting Totals
Third, it gived us a reason to ever want to use Wizard's Communion. Although with a higher duration, as ruled in errata, to account for the casting time of the Ritual itself.
Fourth, withiout the need for Penetration it is too easy to cast a high level Aegis, since casting total does not matter then, and you can simply accept the fatigue loss. Missing the level by less than 10 still means the ritual is cast. So the same Art scores needed to cast a lvl 20 Aegis with pen 20 allows you a lvl 50 Aegis if you don't feel a need to Penetrate.
