Sync both ways with itunes

[younca4]

I'm using tunesync as of right now and it works great but I'm looking for something that will sync both ways. As of right now, if I download files and add them to playlists from the device, it will remove the files when Tunesync syncs because it wasn't on my Mac. I was looking into isyncr but can't find out if it syncs both ways like I'm looking for. Any help would be appreciated...