ssh doesn't "tunnel" data transfers; it uses exactly the same SSL encryption that a web browser does, and probably with less overhead because it's not dealing with RFC822 headers, cookies, and the like. And it uses zlib for compression. Of course, I don't know what else is going on with Foldershare, since it's proprietary. They might be doing something like rsync, which would help with synchronizing large files with small changes, but probably not otherwise.