I can see why you put the time restriction in, but I'm worried that it makes Magi very reluctant to visit each other, even for Tribunal, as the three day acclimatisation to the new Aegis would make them vunerable. My suggestion is "Ummm..."
This is very cool. If I weren't in the middle of running a campaign I would totally start one under these houserules if we can get them hammered out.
Bob