Dropbox does LAN sync, so at home between computers it should be fast, and with documents, i know it just sends the "diff"? of a file so it is pretty darn hasty, also, it does hashes of all of your files you put in your box, so if you put a file in your box that has the same hash as a file already in Dropbox, it will just add the "hash" to your list of files, so it will "upload instantly". These "features" are present in both the free and paid version. I'm pretty sure Dropbox limits it's speed, uploads will generally max my upload (100kb/s) but i'm not sure about yours, for download though, for me it limits to 250kb/s~ (Note, I live in Australia, so maybe it will be better for you). This is really quite tolerable, even for large files, because it does it all in the background.