I've found SurgarSync too unreliable. There have been times when a "sync" just took forever to start for some reason. Dropbox always seems to be "ready and waiting" for all my syncing chores. Another, largely unadvertised, feature of Dropbox is that if two synced devices are on the same local net, file syncing will be very fast as the data is copied directly from machine to machine, as well as to DropBox server. This makes syncing locally VERY fast. Lan Sync: https://www.dropbox.com/help/137/en
From DropBox help:
With LAN syncing, Dropbox will look for the new file on your Local Area Network first, bypassing the need to download the file from Dropbox servers, thus speeding up the syncing process considerably.