How to start syncing two existing directories with git annex?

[Sean Hammond]

Hey, I have a ~/Music directory on computer A, and a ~/Music directory 
on computer B. They contain mostly the same files (and with the same 
paths). But there might be some files on A but not B, or vice-versa. And 
there might be some files on both but different (e.g. different id3 tags).

I want to use git annex assistant to sync the two dirs. Neither computer 
is big enough to hold two copies of the Music dir at once. Ideally, I'd 
prefer not to have to delete the Music dir from computer B, for example, 
and then let git annex sync it from A over to B again.

I've setup git annex assistant on both machines and have them syncing 
their ~/Annex dirs over the local network.

Now how can I start syncing the two music dirs? What will happen if I, 
for example, drag ~/Music into ~/Annex on computer A then, without 
waiting, do the same on B?

I could use unison to make sure that the two ~/Music dirs are exactly 
the same, and resolve any differences, before moving anything into 
~/Annex. Maybe that would be a good idea?

Thanks