The following is a "detail" for the current state of things, but something that should be considered for a change in the longer run.
Keeping in mind the premature awesomeness of MacHg: remove the Save menu!
MacHG adds only one evident feature on top of those already provided by the underlying Hg: a one-click access list of repositories I am working on, showing their remote parents, and possibly(?) -in the case of cloned heavy branches- allowing cross-repository interaction.
This list is the only thing I want the application to remember and keep track of the next time I open it (not counting the app's preferences).
Still, MacHg asks me to save any changes I make to that list in a .mchg document which doesn't seem to serve any other purpose than, ditto, save that list. I think this operation shouldn't be exposed. It is the app's own business to save its state and remember it the next time I open it. Imagine an app that asked you to "Save as..." every time you changed something in the preferences. Wouldn't that feel weird?
When I open MacHG, I shouldn't think that I am using MacHG, rather that I am using one or more of my repositories. I am not working on my files, rather on a meta-description of my documents' current and past state. I am not there to edit the list of the repositories containing my actual documents.
If anyone wants to save different .mchg documents so to group repositories, that seems like a low priority feature to me, and it could be accomplished more elegantly by grouping in the list itself.
MacHg should handle saves the way the Yojimbo and other do: there is no explicit save.
What do you think?