A big point is that if you want a low power saga, you may also want to have a lower stakes, semi soap opera style play more like Downton Abby. The magi are the equivalent of the nobles, with companions and grogs filling in roles around the Manor. The stories involved revolve around personal quirks and motivations. The key point being that the PCs do not feel they are lacking and cannot handle the adventures.
One of the best things you can do is enforce the rules as written. Go on an adventure? Then no more xp or activities for you for the rest of the season if you take adventure XP.
And yes, I agree with all of the above house rules and my personal favorites would be:
- Arts as ability XP.
- All grogs have to be bought with BP.
- No bonus xp virtues including affinities
- No vis sources, all vis requires an adventure to obtain.
- Spring Covenant
- No Summae, only Tractatus
Contrast this with my 1st Crusade campaign. This is an epic save the world blow up lots of Bad and good guys along the way campaign. Adventure xp every session beyond 10xp, piles of virtues, huge rewards of vis, so much money we dont even bother to count it, and powerful books... Countered by powerful enemies. It's alot and not everyone's style.