It might just be worth clarifying the difference between File Sharing and SugarSync.
With File Sharing, suppose you have all your documents in the Documents folder in computer 'A'; you can then access this folder in computer 'B' where it appears like an external hard disk. You can drag documents over to B's Desktop top work on them then copy them back, or indeed you can just open them directly (though this might be just a little slower for editing).
Sugarsync works differently: you would nominate the Documents folder (for example) on both computers. Then if you make a change to a document on computer 'A' the modified document is automatically uploaded via the internet to Sugarsync's server, and from there down to the same folder on computer 'B'. You can modify it there, and the same process will bring the copy on 'A' into line.
All this happens seamlessly in the background but there are two important points to grasp. One is that the process takes time - it's rather assumed that you will keep both Macs on at all times. If you have the laptop shut down, when you boot it up the changed documents will be downloaded. If you try to edit a document before the changed version has had time to download you will erase one or other set of changes, so you need to be aware of the delay. The other point is that the folders are fully synced. This means that if you delete a document on computer A it will shortly be deleted on computer B as well - this sounds obvious but it's the sort of thing that catches people out, thinking that if they delete a document by accident there will still be a copy on the other computer.
One big advantage of Sugarsync is that the laptop doesn't have to be at home: you can stay in sync anywhere there is an internet connection. The SugarSync application needs to be running at all times.
The advantage of File Sharing is that you are not dependent on the internet, and that access is quick; obviously it only works as long as the laptop is at home.
The advantages of iCloud... in this context, none.
