well,

with a setting it is allowed to auto-merge or not.
Even if it would be an auto-merge I sure want to see what the changes are.

It could work but it's just what Joost say: I would like to see what the changes are.

What to do if there are changes in the same 'stuff' when auto merge is on?

Im not considering the mentioned setting, i was suggesting the following:
-When publishing espace, it should evaluate if merge is required.
-If merge is required, evaluate if auto-merge can be performed, if so show options on dialog to Auto-merge or Merge or Dont Merge
-Auto-merge option should only appear if after evaluation the outcome is different "stuff" between espaces

So another option when you click a ONE click publish button :)

Something like "Include everything I didn't touch" would be great also.