Bittorent sync? Discoverability and multiple folder syncing has been a problem for me. I would be very interested in a perfect method to track and sync multiple folders on multiple computers

Too bad it's closed.

I use BitTorrent sync on a box and installed ownCloud as the UI to access those files from a browser. It works well.

There is: http://www.emitcloud.com

nice solution

Just use any WebDAV share and sync with anything you want like rsync.

Seafile has been flawless for me.

Seconded - we have been running Seafile for the last few months with several shared folders. It works flawlessly and is quite fast.

I highly recommend Syncthing.

Is forwarding ports required to get syncthing working?

Often not. It can do UPnP automatically. But in my case I don't even need that, because I just run a dedicated server node with a public IP, and everybody else can sync via that.