Thanks for the insights, Peer. All good sense.
I try hard to distinguish my recommendations from my "rules". I do not have a "rule" on whether a Repository should be oriented to a single root aggregate entity (Peer's approach) or to a module-based collection of collaborating aggregate entities (the approach I recommended). I don't have a "rule" about whether a Repository should be allowed to save or not (I have done both and probably will again).
Many roads can get you home.
I will tell you when I think a road leads through the swamp.
As Peer says, you have to accumulate experience and read what other folks are doing.
All the best,