Difference between Astral Projection and Window

[baruk]

I'm using astral projection quite a lot in a current game as Caelum. I found the crystal amazons early, and mass produced the astral 1 priestesses for research. After completing all research, they have become fairly expendable, so I've been using the pristesses to cast astral projection. I have the chalice in the same province, so they recover from feeblemind quickly.
The feebleminding also gives the positions of enemy astral mages. Since astral mages tend to have low hp, I pepper those provinces with seeking arrows. If I had astral 4 mages to spare, I could use them to mind hunt provinces that failed to feeblemind my projectionists.